Kosuke Kisakata is the leader of the Sons of Chaos and is a legendary hacker. He is known by the name Tartarus (タルタロス Tarutarosu?). Very few people know his actual name and he usually uses fake accounts to hide his identity. When he was a teenager he was partnered to a Tentomon, and in the past he also had two two unknown Mega level Digimon. In the present, his partners are Dorumon and BlackAgumon — BlackAgumon formerly belonging to his fiancée.



Kosuke Kisakata

Name used in Digimon Seekers.


Digimon Seekers[]

During his time at University, Kosuke studied and worked under Tomonori Ryusenji. During that time, he dated Tomonori's daughter — Saya Ryusenji. Unit 11: Digital Missing In Action Chapter 3-2 Ryusenji Laboratories was able to vault to the forefront of Digital World research shortly after its discovery due to the hard work of Tomonori's students: Kosuke, Saya, and Shuu Yulin. Unit 11: Digital Missing In Action Chapter 3-3

One day, when Yulin arrived at Ryusenji Laboratories and delivered the mail to the professor, who was busy analyzing some code. He complains about the code itself being awful, expressing shock that it was probably written by Ryusenji himself. As they discuss Yulin's request for a proper server room, the campus being transferred to Denrin, and the new investments in their field around the world, Ryusenji lets her know that since the campus was going to be moved, all requests such as the server room were rejected since it'd be seen as a waste of money. Yulin questions if they will have to go overseas, prompting an annoyed response by Kosuke, who once again had slept in the office. As Yulin calls him out for his habits, Saya arrives with food for everyone and a change of clothes for Kosuke. Unit 11: Digital Missing In Action Chapter 3-2

As the group eat the food Saya had brought them, Yulin scolds Saya for coddling Kosuke too much though she fires back about how she is his wife and not his mother (though they were still dating, not married[1]). Tomonori laughs at the group's interactions, with the group moving on to talk about their research. Since Digimon didn't live very long, research wasn't going well and they figured they needed to find a way to breed and raise their own Digimon to make studying them easier. Saya mentions that if they really are living creatures they could raise them like pets, though Yulin points out she didn't feel that way herself. As they muse that extra-terrestrial life was actually on the Internet the whole time Tomonori laments that they will need money to be able to continue their research — something everyone is able to agree to. Fully devoted to this cause, Tomonori announces that he is going to start a company and as they doubt his ability to Kosuke brings up that the University had money set aside for start up companies which they should be able to use for this end if they were able to convince them to back the project. They decide Yulin should make the pitch since she was trilingual and good at presentations but Yulin herself was worried someone with Chinese ancestry doing so would ruin the entire plan. She winds up agreeing to do so as the others let her know that it didn't matter and she was the only one who could do it.

Some time later, having found a new office, Ryusenji Laboratories prepared to start their move. Kosuke tells the others the they wont see much of him as he would be "fighting on the front lines", with Saya disappointed with the fact he didn't have enough credits to graduate yet. Kosuke muses that it doesn't really matter as he doesn't mind staying at the University for a few more years with Tomonori saying he will hire him regardless of if he graduates. Saya protests, saying that's not something a professor should say — but he simply laughs saying maybe she's right. Unit 11: Digital Missing In Action Chapter 3-3

Tomonori Ryusenji and his students were able to get permission to use a warehouse within the Denrin District as a temporary base for their work despite the fact it was going to be destroyed for redevelopment soon. The group redecorate and replace the name plates with it acting as the headquarters for not just the University but Ryusenji Electrics as well. Tomonori was very happy, since he was now running his own business — even with the massive debts he had incurred setting it up. They had managed to set it up with a mix of University funds, money from the government, and Tomonori's own money — the biggest amount coming from Tomonori himself. Now they had managed to set things up, the group were ready to use Digimon to unlock something significant for humanity.

Some time later, Ryusenji shows off the fruits of his labor — the Digimon Dock. He intended to use it to record the actions of the Digimon, though none of his students were impressed with it. Since the Digimon die fast on their computers, he wondered if he could recreate their habitat as closely as possible within something else — hoping the Dock would be able to help with that. He decided to make it a toy, as he wanted children all over the World to be able to become friends with Digimon. When he refers to the Digimon as humanity’s irreplaceable companions, Yulin becomes enamoured with the idea and when Saya notices this she gives her a Digimon Dock. Yulin is surprised to see a Digitama on it, with Saya and Tomonori explaining they had found it on the Internet and that the Dock was able to display the data itself instead of as a series of numbers like on their computers. The group are amazed at the sight, and become even more excited when the Digitama begins to move. Thinking it was going to hatch, Tomonori snatches it out of their hands as he wanted to see. Unit 11: Digital Missing In Action Chapter 3-4

Tomonori was promoted to being a full time professor at the University. In addition, a big tech company invested so much money in his work it allowed Ryusenji Electronics to become a proper business. Tomonori was able to hire more staff and as the company got bigger they realized they needed to move on from the rented warehouse. Unit 11: Digital Missing In Action Chapter 3-5

At some point, Kosuke proposed to Saya and she accepted. Unit 11: Digital Missing In Action Chapter 3-5

Saya and Yulin discuss and celebrate the fact that Kosuke had proposed to her. They then discuss the new employees at Ryusenji Electronics and the fact that the company would need to go public to pay back their investors since thus far they hadn't actually made any money. Kosuke joins the conversation, joking that Yulin was trying to steal Sara from him, and shows off a VR headset. He puts it onto Saya's head and tells her that she is currently seeing through a Digimon's eyes and can see what it can see — though it was a recording rather than live.

Wanting to one day explore the Digital World, Tomonori continues to work even harder. Wanting to experience all five senses whilst there, he began researching DigiCores in the hopes he could transfer human consciousness into it and allow his goal to come true. He found it was possible too, as other scientists were researching ways to convert the human consciousness and memories into data. There were even machines that would allow blind people to access sight, or deaf people to access hearing though the government had made it so that they couldn't move past research for around 10-20 years. Tomonori figured however, that since the Digital World was a different World, those rules wouldn't apply which lead him to focus his time on this endeavour and would focus on it even if it took him the rest of his life. To make sure no one would find out and stop him, the company researched it in secret.

Some time later, Saya would become the first person to do a Mindlink — linking her mind with a Digimon — though the effects on her body were bad with her vomiting and defecating herself in front of everyone. As she did more and more Mindlinks her body got used to it and the side effects would be less severe. Upon coming too, she looks into her Digimon Dock and praises her BlackAgumon for its hard work. Yulin and Kosuke had also been given their own Digimon partners, with Kosuke's turning his life around since he had to make sure he was able to properly look after Tentomon. Unit 11: Digital Missing In Action Chapter 3-5

All three of them would go through many Mindlink tests though thus far had only explored their Digimon Docks. To be able to explore further than that, and reach the Digital World, they would need better computers. They would also need to learn how to control their partners, since if they lost control they would go passed the Mindlink limit and be unable to return to their bodies. As they discuss these facts, they also theorize what the Digital World would actually be like.

Kosuke was in charge of the development of the Digimon tools and would send Digimon out to the Digital World to explore. Around 80% of the Digimon would return alive, giving them lots of useful information. Tomonori muses that it would be impossible for such tests to be 100% successful, comparing it to space mission in the past — this making the students uncomfortable since he brought up instances of astronauts failing to come back especially since they would soon be joining the Digimon on their travels via Mindlinking. They would refer to said upcoming Mindlinking project as the Tartarus program.

The night before beginning the Tartarus program Yulin, Saya, and Kosuke visit the plot of land on which Tokyo University of Electrical and Computer Engineering was to be built in the Denrin District and look on in amazement that such University was going to be built there. As they take in view of its current appearance, before the building would be made, Saya makes a wish that everyone would still be together in ten years — including their Digimon partners. She shows off the area to her BlackAgumon, by pointing her Digimon Dock at it, and makes another wish that the Digimon will be able to live alongside the humans. Yulin is confused at the fact Saya was talking to her BlackAgumon, since they can't talk back, but she tells them that BlackAgumon had actually been talking to her during their Mindlinks — a fact that shocked Yulin. Realizing what she had said, she tells Yulin not to tell anyone as she was scared she would be seen as crazy and be removed from the project. She tells her that BlackAgumon would call out her name and tell her she's glad she came to play and this leads Yulin to think Digimon might actually be dangerous and that they were actually the ones discovering humans, not the other way round. Saya points out it was too late now though, and that their Worlds were now destined to collide. She also tells Yulin she is considered the most important member of the team as Saya was Tomonori's daughter and Kosuke was just a younger version of him. In addition, she was considered to be the only one to be to stop them should they mess up. Kosuke joins them, giving them warm drinks, and though he tries to get them to leave due to the weather Saya insists they stay longer. Yulin leaves, returning to the car to warm up, and with the couple now on their own, they act like love birds which irritates Yulin and causes her to take a picture of them.

The next day, Yulin, Kosuke, and Saya Mindlink to their partners. They have their partners board the Tartarus probe, a digital observation vessel so that they could begin the Tartarus program. Unit 11: Digital Missing In Action Chapter 3-6 The Digimon search the Digital World on their own virtual vessels with their partners controlling the vessels using Kosuke Kisakata tools. Due to the weak technology being used, the groups visibility was low but despite this they followed the path set for them and continued on their journey. As they explored, they were attacked with Kosuke and Yulin having no clue what had attacked them. Yulin and Kosuke figure BlackAgumon had been the attack target, and were unable to do anything as Saya's unit vanished without a trace. Kosuke blamed himself, as he had been the one to push for her to be a one woman rescue team, and regretted it wishing he had been doing it instead so that she would've returned safe in place of him. Tomonori forces Kosuke and Yulin to retreat as he considered it far too dangerous to have them try and rescue his daughter. The Tartarus probe was damaged and Palmon and Tentomon were injured and as such he had them withdraw as the chance of all three of them falling into DMIA was too high. When they logged out, Kosuke cried as he held his unresponsive fiancée. Her consciousness had fused with BlackAgumon's DigiCore, and BlackAgumon's whereabouts was unknown. Now in a coma, her body was sent to the local hospital with no hopes of her ever waking up. Unit 11: Digital Missing In Action Chapter 3-7

Over the following years, Tomonori made sure to keep Saya's body in a stable condition. He sent her to a hospital in the United States that specialized in coma patients then continued the Tartarus program and Mindlink tests in secret — though without the help of Yulin and Kosuke as he didn't want to put them in any more danger. Despite losing Saya, most aware of what happened considered the project a success as they had managed to capture footage of the Digital World and their programs allowing control of their Digimon worked as intended. Yulin and Kosuke didn't feel this way though, and considered it a failure. Kosuke cut contact with Yulin, and dropped out of University — though still kept in contact with Tomonori. Unit 11: Digital Missing In Action Chapter 3-7

Many years later, and the Digimon Dock was a success. Many people had befriended and raised Digimon and and it did indeed allow them to live longer. More and more sponsors poured money into Tomonori's research and with more money, Tomonori was able to increase his influence within the University. The extra money also allowed the University itself continued to grow. Unit 11: Digital Missing In Action Chapter 3-4

At some point during Dorumon and Kosuke's partnership, many years before they lead the group known as the Sons of Chaos, Dorumon told Kosuke about the Sacred Chalice, which Dorumon claimed would be able to save Saya Ryusenji. This lead to Kosuke dedicating the next few years of his life to getting it. Sons of Chaos: Seekers Chapter 4-4

Some time after learning about the Chalice, Kosuke lead a group hackers — with those hackers later forming the core of the SoC. Kosuke and his Hacker friends, Mindlinked to their partner Digimon, found themselves in the Gateway within the Wall Slums, looking to hack into an impenetrable firewall. It was going well but took a turn for the worst when a the system administrator discovered them which lead to the admin sending a group of gatekeeper Digimon to attack them. Megadramon and Marvin Jackson defeat most of them but they are quickly replaced with more. As they had already been Mindlinking for a while, Marvin tells Kosuke he wasn't going to be able to hold off the horde for much longer. All of the hackers, sans Kosuke, had their Digimon at the Ultimate level, but even that wouldn't be enough to defeat thousands of Digimon. Kosuke declares it was time for Phase 3, and had Dorumon digivolve to the Ultimate level DoruGreymon. DoruGreymon charges up its Metal Meteor attack, which has Marvin realize that Kosuke wasn't playing around. He has the other hackers scatter with Megadramon and the other partner Digimon firing attacks at the gatekeeper Digimon in the air. Kosuke begins a hack, which causes all the gatekeeper Digimon to be sucked under the Metal Meteor. They try to resist but to no avail, with it landing on them and killing most of them. Marvin and the others take out the survivors but when their hacking reaches 30%, it stops. Kosuke asks what happened, with DoruGreymon telling his partner that they could only get to 30% with one Prototype Digimon. Not just that, to be able to successfully hack into the system they would need three Prototype Digimon at the Ultimate level with the three needing to consist of Vaccine, Data, and Virus Digimon. Kosuke thinks and figures out that with DoruGreymon a Data Attribute and Shuu Yulin's Ryudamon a Vaccine they would need one more Digimon — a Virus. The gateway had been there even before the Wall Slums themselves, which is why it required such Digimon. Beyond the gateway was the source code, and Kosuke wanted it so that he could change the World. As they muse over Kosuke's goals, one of the Royal Knights shows up and — knowing full well they had no chance against a member of the Royal Knights — tells everyone to flee. Unit 11: Digital Missing In Action Chapter 3-1

He eventually went on to create the hacker group known as the Sons of Chaos.

Though Kosuke sets up the SoC's missions, he rarely gets involved himself. Hacker Leon: WWW Airlines flight 626 Chapter 2-2

At some point, the Sons of Chaos had struck with deal with Tomonori to try and make a cure for DMIA. The SoC would provide the needed drugs, and he in return would give them the data on the trials. Over the many years, they are able to make a prototype medicine — though it would need to be applied to the Digimon — and it had originally been made to extend the amount of time one could safely Mindlink. Theoretically it would peel the human consciousness away from the Digimon's DigiCore, granting a window for the human's self-awareness to return, which they hope would allow them to heal someone of DMIA. They had run tests on Digimon with AI copies of human data and had found that it was possible to separate the human from the Digimon. Unit 11: Digital Missing In Action Chapter 3-11

Obsessed with finding BlackAgumon, he puts up a mission with a 1 million DC reward for anyone that can get him one. Hacker Leon: WWW Airlines flight 626 Chapter 2-2

When Eiji Nagasumi applies to join the Sons of Chaos he has to pass a test assigned by a member of the group to be allowed to join the group, and Tartarus, the leader of the group, is chosen as the one to give Eiji his test. Eiji: Wolf of the Ninth Avenue Chapter 1-12 This was because Kosuke and Dorumon knew Eiji and Loogamon were working as spies for Tomonori and, despite that, wanted them in the group as they needed Eiji's muscle and knew they could trust him because he was working for Ryusenji. Unit 11: Digital Missing In Action Chapter 3-10

Tartarus does the interview with him (Eiji unaware of this fact, as Tartarus was using a generic account) with Tartarus telling him that he can only join if he is a good code cracker, to which Eiji asks if he is whether that would allow him to meet Tartarus. Tartarus finds this curious, though Eiji insists that since Tartarus is so well known anyone would want to meet them. Tartarus tells him that if he is really good, one of the higher ups would eventually contact him and allow him to meet Tartarus but that very few members had actually managed to meet him. Tartarus sends Eiji an exam, and tells him to complete it. Eiji finds that the mission is named "A Wolf at the Back Gate", which he finds odd since he has Loogamon, though doesn't mention that fact. Tartarus tells him that nine out of ten people who do the exam lose their Digimon, and they would not insure his Digimon for him or pay compensation should he lose his Digimon. Eiji wasn't deterred though and proceeds to Mindlink. Eiji: Wolf of the Ninth Avenue Chapter 1-9

Tartarus waits for Eiji on top of a building whilst Mindlinked to Dorumon, who hides under a cloak to hide its identity (though this fails, as Loogamon actually noticed it was Dorumon Unit 11: Digital Missing In Action Chapter 3-10). Eiji, Mindlinked within Loogamon, arrives two minutes late which causes Tartarus to dock him two points on the mission. Eiji suddenly appears next to Loogamon, which surprises even Loogamon. Eiji explains he had remembered he was told he could access commands on virtual monitors by thinking of doing it and having seen a button saying hololize simply thought of pressing it which allowed him to hololize next to Loogamon. Tartarus was also surprised and tells Eiji that his mission is to create a map of Ninth Avenue for them, and that he just has to walk around the area with the provided map tool as it would auto fill the information for him. Loogamon laughs, and informs Eiji that the mission was perfect as it had something it needed to do in Ninth Avenue anyway. Tartarus wishes Eiji luck on his mission, hoping he would be able to pass and become a member of the group. Eiji: Wolf of the Ninth Avenue Chapter 1-12

As they watch Eiji and Loogamon leave, Dorumon tells Tartarus it was surprised Eiji was also Mindlinking to which Tartarus expresses surprise at not just that but the fact that Eiji had already shown up with his limits unlocked. It wonders if Loogamon had noticed they were also using Mindlink then asks why Tartarus had given the Demon Wolf of the Castle of Nine Wolves such an easy mission. The SoC member realizes Dorumon was right and contacts the DigiPolice, telling there where Eiji was. Eiji: Wolf of the Ninth Avenue Chapter 1-13 Eiji: Wolf of the Ninth Avenue Chapter 1-17

When Eiji and Loogamon arrive at the Castle of Nine Wolves they are intercepted by the DigiPolice who ask to talk to him on GriMM. Turning down the request would be seen as going against the DigiPolice but Eiji had no choice in the matter as his means of communication during the mission was in the hands of Tartarus who proceeds to turn down the request. Eiji: Wolf of the Ninth Avenue Chapter 1-14

Dorumon and Tartarus, still Mindlinked, watch in awe as Eiji and Loogarmon defeat the DigiPolice. After the two of them leave, Dorumon chastises Tartarus for telling the DigiPolice about Eiji, though he just muses that he was right about how powerful Loogamon was. He notices that Eiji had completed the mission having sent him the map data, and decides to accept him as an official member of the Sons of Chaos in the hopes that Eiji will be able to lead Loogamon into become an even more powerful Digimon. The wind then blows off Dorumon's cloak. Eiji: Wolf of the Ninth Avenue Chapter 1-17

The members of Operation Infinity meet up in Marvin's SoC GrimM room, with there being eight users there total. The monitor displays the mission, which is to hack X Nation's server. Hackers from X Nation had performed lots of cyberattacks and had even recently stolen billions worth of cryptocurrency. Since the SoC use cryptocurrency they couldn't turn a blind eye to them doing such a thing, especially if it caused a major shift in the World's financial powers. The SoC plan to destabilise X Nation's leader as well as get revenge on them, as they had done crimes using a Machinedramon and framed the SoC. Tartarus arrives, introduces himself as the leader of the SoC to the new members, and then tells them to render their server useless and capture their Machinedramon. Hacker Leon: WWW Airlines flight 626 Chapter 2-3

The SoC's plan to get revenge on X Nation for framing them for crimes they didn't commit by hacking into their servers and stealing their Machinedramon ends in failure after Leon Alexander and Kazuchimon defeat them, and also kill the Machinedramon. Shortly after the failed mission Dorumon and the Hololized Tartarus, who was using his interviewer account, visit Marvin Jackson is in his room in the Sons of Chaos GrimM channel. Dorumon asks how Megadramon was, with Marvin stating that it was okay but would be out of action for a while due to the injuries it had sustained at the hands of Kazuchimon. He tells Dorumon that Eiji, the hacker that Tartarus had personally scouted, had saved him and wonders if he should retire having lost that badly. Social media had become ablaze with rumours about how Judge had single handedly defeated the SoC, with the SoC themselves having leaked this information. Dorumon and Tartarus tell Marvin they would not let Judge get away with it and would get revenge against him as he poses a threat against not just the SoC but the entire Crack Team. Marvin asks if the duo are going to go ahead with their plan for an all out war, with them confirming that even with the loss of Machinedramon the final piece of the puzzle had still fallen into place. They discuss Eiji and Loogamon, saying that they had only seem him digivolve to Champion and as such didn't know whether they could trust them to stick with them till the bitter end without seeing their full power. He asks Marvin if he is still dedicated seeing Tartarus's plan to the end, to which Marvin confirms he is. Hacker Leon: WWW Airlines flight 626 Chapter 2-6

Tartarus sends Eiji a message, praising him for his work during the attack on X Nation's server with Tartarus stating he wants to hire Eiji again in the future. He asks Eiji to get revenge against Judge for interrupting their mission since failing to retaliate would lower the image of the SoC. Hacker Leon: WWW Airlines flight 626 Chapter 2-9 He allows Eiji to determine Leon's punishment, with Eiji stating he would only do so under those conditions. He comes to the agreement that if he could get Leon to agree to never interfere with the SoC again, they'd let him get away with just an apology. He otherwise, would have to take Leon out. Hacker Leon: WWW Airlines flight 626 Chapter 2-10 Eiji is unable to come to an agreement with him, leading to a battle in which Leon overuses his Mindlink causing him to become DMIA and fall into a coma. Presumably unaware that Omegamon of the Royal Knights had shown up in the middle of their battle and Leon had sacrificed himself to save Eiji from it Tartarus sends Eiji a message congratulating him on taking out Leon, telling him he was the hero of the Sons of Chaos. Hacker Leon: WWW Airlines flight 626 Chapter 2-Intermission

A few days later, Kosuke goes to a store near to Eiji apartment's and buys a bunch of supplies. He then goes to Eiji's apartment and rings the doorbell. Eiji looks through his monitor to see who it was, though the only part he could see of Kosuke was his shoulder as he had stepped back.

Kosuke messages Eiji to tell him that he was there, and as Eiji pretends to not be in Kosuke states he knew Eiji was home. Loogamon uses its hacking powers to open the door anyway, excited at the fact the leader of the SoC was at Eiji's house, and Kosuke asks if he can come in though goes inside anyway when Eiji takes too long to answer. He compliments Eiji's apartment, pays his respects to Eiji's deceased parents, and then brings up WWW Airlines flight 626 — the flight which Eiji's parents were on when they died. He gives Eiji the supplies, figuring Eiji needed them, and explains that he was in the same state after someone close to him (Saya Ryusenji) had gone into DMIA as well so knew Eiji needed the help. Eiji is shocked, since he had heard that no one had ever DMIAed whilst working for Tartarus, and as Eiji's stomach growls due to the food Kosuke points out that meant he had the will to live and as such should get his life back in order. Seeing that Tartaus was right, Eiji starts to eat the food. Unit 11: Digital Missing In Action Chapter 3-9

After finishing the food, Eiji Nagasumi has a shower. Whilst he does so, Loogamon keeps Kosuke company.

As Eiji returns, he realizes how much of a mess his apartment is and apologizes — though Kosuke laughs and says his is the same and apologizes for showing up uninvited. Eiji asks who Kosuke is, though he only uses the name Tartarus rather than use his real name. Eiji introduces himself with his actual name and asks if there's any proof that Tartarus really is who he says he is. He summons Dorumon, with Loogamon recognizing it as the Digimon who had given them the test to join the Sons of Chaos. Eiji, remembering it was a random guy who had interviewed them, disputes that this proves he was Tartarus — though Dorumon insists he is and that the interviewer account was just an alternate account Tartarus sometimes uses. Though he still wasn't sure if it was actually Tartarus, Eiji knew very few people know of the test in the first place so at the least knew it was someone high up in the group even if it wasn't Tartarus himself. He asks why Tartarus, the leader of the SoC, would oversee the test of a newcomer himself and figures that must've meant he knew why Eiji was applying in the first place — as a spy of Tomonori Ryusenji. Dorumon laughs, and reveals that they knew the entire time that Eiji and Loogamon were spies. Eiji asks why they would let him join knowing this, to which Kosuke says they needed Eiji's muscle and knew they could trust him because he was working for Ryusenji. He thanks him for saving Marvin's life in their previous mission, whilst Dorumon tells him he also had another reason to accept him into the SoC and that accepting him into it would allow them to put Tartarus' plan into action. Loogamon resent this, not wanting to go along with someone else's plan — and tells them that their goal was to rescue Leon and Pulsemon. Dorumon tells them that's exactly why they were here, which causes Eiji to realize he would have to work with them to be able to save his friend. Dorumon points out that it was Tartarus himself who requested Leon to be taken out and that Eiji wanting to save Leon meant they actually had the same goal as Tartarus as he too wanted to save someone who had gone into DMIA and that that was the entire reason the SoC was even formed in the first place. Eiji is surprised to hear this, and, going back to his previous thought, brings up the fact that he had heard no one had ever gone DMIA during a mission attended by Tartarus — since this would mean that wasn't true. Tartarus says the story was misunderstood and that he was the first person to lose someone to DMIA and had made sure that he would lose no one else to it again. Eiji asks for more information, to which Tartarus agrees to share his story. Unit 11: Digital Missing In Action Chapter 3-10 Kosuke tells Eiji his real name with Dorumon surprised at the fact its partner had done this but Kosuke simply states he thought it was fair since he knew Eiji's real name. He was also happy he got to use his real name for once, since he usually had to hide his identity due to being the leader of the Sons of Chaos. He tells Eiji about what happened to Saya, though doesn't actually say who it happened to and leaves her identity vague. He brings up the job listing for someone to find a BlackAgumon, a listing Eiji recognized, and explains that he was looking for it because the person he lost was the partner of it. He explains that the person's body had been moved abroad to receive special care and that he had gotten no leads on the BlackAgumon despite how many years had passed. Eiji asks if he could restore his friend should they find the BlackAgumon and Kosuke brings up a file with the prototype DMIA medicine on it.

Eiji was confused as to why Code Crackers would work on such a thing, to which Kosuke explains their deal with Tomonori. Eiji was surprised Kosuke would do this, since a failed product could kill the person they were trying to save, though Kosuke brings up a video of Saya's unconscious body and explains that the drug was what was giving him hope. This has Eiji realize just how much Kosuke trusts Tomonori and this in turn causes Eiji to trust Kosuke. Dorumon asks if that means they will work together, to which Eiji and Loogamon agree. Eiji asks if they have enough of the drug to help both Leon and Kosuke's friend but he informs them they only had the one. Eiji says he will just ask Tomonori to make another one, though Kosuke insists it's fine as they just needed to focus on finding Pulsemon for now. Eiji declares it was time for them to come up with a plan, but Kosuke tells him to instead come with him as he already had a car ready and that they need to leave since the DigiPolice would be arriving soon. As they return to the car, Kosuke tells Eiji they were going to reboot Operation Tartarus — though Eiji had no idea what that was. Kosuke tells Eiji he will have to say goodbye to his old life, to which Eiji is more than happy to as his old life was awful. After a short friendship pledge with Loogamon, Eiji gets into the car with Kosuke telling him they were going to the Gateway to code crack their way into the depths of the Digital World. Unit 11: Digital Missing In Action Chapter 3-11

Kosuke is able to use his charisma to convince multiple branches of the Crack Team to work together on their mission whilst Eiji and Loogamon go to Ninth Avenue and convince Loogamon's minions to join in on the plan. The duo are then able to convince other Digimon in the Wall Slums to join too with them all agreeing to join the uprising since it was the chance for them to return to the Digital World having been banned from returning due to being contaminated with data from the human world.

The SoC live stream the hacking, which attracts the attention of the DigiPolice. Wanting to stop them, Yulin and Satski send the DigiPolice out to attack them. As they fight the Hacker Digimon, Yulin asks for an update but learns that no members of the Sons of Chaos were actually present and instead Digimon that live in the Wall Slums were taking part in the battle alongside the Crack Team. The DigiPolice are surprised, with Ryudamon stating it had learned why they had joined. Not wanting to let the Sons of Chaos win, Yulin sends in even more units to the battle. She also tells them that they are not allowed to fight Tartarus/Dorumon and that they should tell her immediately so that she could fight them herself.

As the battle continues, the Mindlinked Marvin and Kosuke watch on as thousands of Digimon fight the gatekeepers. As Loogamon and Eiji ride the train back from Ninth Avenue Kosuke calls and praises them for having convinced the Wall Slum Digimon to join their cause. As they end the call, a member of the SoC contacts Kosuke and tells him that the DigiPolice had found the duo's location. They prepare for battle, with Kosuke saying they have to win or else they will never see their partners again alongside the fact he would never see Saya again. This was just as Kosuke had wanted though, as he needed Yulin and Ryudamon for his plan and had actually set a trap for them. Dorumon begins to digivolve, with Kosuke declaring he would achieve his goal and find Saya's BlackAgumon so that he could save her. Unit 11: Digital Missing In Action Chapter 3-12

Dorumon warp digivolves to Dorugoramon then remains in the nearby caldera — with the duo watching the battle from their vantage point. As they watch, they are ambushed by Ouryumon. Dorugoramon survives, to the shock of the Mindlinked Yulin, with the former comrades having back and forth banter. As the two Mega level Digimon fight, Ouryumon deflects one of Dorugoramon's attacks — with the attack carrying on, taking out a large amount of Gatekeeper and Crack Team Digimon. It continues even further still, and collides with the wall of the caldera — creating a hole in it. The hole was so big, it causes the wall to start crumbling. Sons of Chaos: Seekers Chapter 4-1 The duo continue to fight, with the fight now in the air. They find themselves directly above where Eiji and Loogarmon were fighting Tachibana and Sakurada's ​​Hi-Commandramon and Kosuke, despite being in the middle of a battle with Yulin, yells out from above for the duo to achieve their ultimate forms — with this motivating Eiji and Loogamon and having them decide they were now actually ready to handle Ultimate level power. This motivation allows Loogarmon to digivolve to Soloogarmon. Sons of Chaos: Seekers Chapter 4-2

The light of the digivolution had been so bright, it put a stop to the fight between Dorugoramon and Ouryumon. Yulin was surprised to see Eiji had achieved the Ultimate level, whilst Kosuke celebrated the fact. Yulin would quickly snap out of it, reminding Kosuke that they were in the middle of a fight — to which Kosuke informs her he never intended to fight her in the first place and instead she was part of his plan. Demanding an explanation, he tells her that they now have three Prototype Digimon at the Ultimate level — with them being Vaccine, Data, and Virus Attributes. Having no clue where he was going with this, she asks what's he's plotting though he tells her he was not plotting anything and was moving onto the next phase of Operation Tartarus and he had not given up on Saya. She tries to comfort him over the loss of Saya, but he snaps at her and tells her she knows nothing about the current version of him. Realizing that Kosuke needed Ouryumon for his plan, she figures out that Kosuke was unable to win their current fight — to which he confirms. Yulin argues back that she will be the one to save Saya, not him, but he informs her that Operation Tartarus would save her and that Dorumon was the one that had told him about it. He would go to depths of the depths of the Digital World and find the Sacred Chalice, which Dorumon claims will be able to save her. Despite the reveals, the fight continues but just as Ouryumon was primed to score the killing blow — Yulin hesitates, with Kosuke telling her she will not be able to kill him. Not because she's a cop, and as such would not want to kill someone, but because by killing him Saya would die too as he was the only one who would be able to save her. Since Ouryumon's killing blow failed, it became an easy win for Dorugoramon — who defeats Ouryumon with a counter attack. Sons of Chaos: Seekers Chapter 4-3

Ouryumon de-digivolves to Ryudamon, and having won, Dorugoramon de-digivolves to Dorumon and checks on Ryudamon to make sure it's still alive. Figuring he still needed to keep them out of his way, Kosuke uses a program to restrain Ryudamon — just in case it were to awaken. With phase 2 of Operation Tartarus now complete, Kosuke declares it was now time to start phase 3. He contacts Marvin and asks if he's still alive, to which he confirms he is. He then learns about how the rest of the battle was going — the DigiPolice had around a third of its members left, whilst the only remaining members of the Sons of Chaos were Kosuke, Marvin, Eiji, and a few of the other leaders. Though some members of the Crack Team and Wall Slum Digimon remained, there weren't enough of them for them to guarantee a win against both the DigiPolice and the Gatekeeper Digimon. Dorumon tells Marvin to bring Eiji to them, with Marvin asking if they were going to use "you know what". Upon hearing confirmation they would, Marvin activates a tool from his suit — with a loud roar being heard.

Marvin and Airdramon deliver Eiji and Loogamon to Tartarus, then leave to return to the battlefield. The other SoC leaders with Kosuke log out, with all of them having things to do in the real World. Tartarus thanks them for their work, with the only ones remaining being Kosuke, Eiji, and the unconscious Ryudamon. Eiji looks on, and sees the DigiPolice retreating. He sees Ryudamon and asks if it was alive, to which Kosuke confirms it is. He asks what they need to do next, with Kosuke stating the next step was to crack into the gateway. He states they need to use the interfaces of the three Prototype Digimon, and that the fact they were so old meant the Digital World hadn't accounted for them which would make their hacking easier. He tells him of how he needs Vaccine, Data, and Virus Prototype Digimon and that all three of them were now present. Eiji asks what he and Loogamon needed to do, but he tells them they don't need to to anything — to their disappointment. The only thing that was needed was their presence, and they could just watch as Kosuke did the hacking. This has Eiji realize that's why Ryudamon was restrained, it didn't need to be awake or even do anything — it simply just had to be there.

Loogamon, Dorumon, and an unconscious Ryudamon form a circle around a Hololized Tartarus — with Eiji complaining and saying if they had told him about all this from the start, he would've helped. Kosuke tells him that that wouldn't have worked, since they needed all three Prototypes to be able to digivolve to Ultimate, and he had only recently achieved that stage. Kosuke begins the hacking once Marvin returns, and, as Loogamon and Dorumon would be unable to fight during the process — Marvin and the other SoC members with Marvin were the only defence they had. Marvin hadn't returned to Kosuke alone, he and the SoC members he brought with him brought a Chaosdramon. Within seconds of arriving, it attacks the nearby Gatekeeper Digimon — taking them out with ease. Eiji wonders who was Mindlinking with it, but Marvin tells him no one was as it was too volatile and instead — he himself was controlling it with a bot. With no more enemies at the current point, he has Chaosdramon go on standby, but warns Kosuke that "you know who" would show up soon. With no enemies currently in sight, Kosuke begins hacking. Sons of Chaos: Seekers Chapter 4-4

As Kosuke continues hacking into the system, the Sons of Chaos are attacked by Gatekeeper Digimon. Chaosdramon and the SoC hackers Marvin brought with him are able to deal with them however, with Kosuke's hacking at 33% — which was 3% higher than when he had tried it in the past with only Dorumon.

Gatekeeper Digimon continue to arrive, but the SoC deal with them every time. As more and more fights happen, Kosuke hacks even more, now at 66%. Loogamon senses something, and tells the others that "it's coming". As Eiji worries about Loogamon's warning, Dorumon tells them there's nothing they can do about it, with the situation becoming worse as their SoC allies needed to log out due to their Mindlink times running out. This would leave Marvin as the last line of defence. Before they can log out, they are attacked by a Mekanorimon. Eiji was confused, since he thought the DigiPolice had retreated, and quickly learns that it was being piloted by a Mindlinked Satsuki/Numemon. The Mekanorimon collapses, being heavily damaged, but had still been able to do this last attack. Numemon gets out of the now fallen Digimon, with Marvin asking why she was here. She tells him she was here to recuse Yulin, with Marvin laughing as she only had a Numemon with her. This wasn't the case though, and she pulls out a Digimon Dock and tells the unconscious Yulin/Ryudamon that she had tendered her resignation as she had broken the rules of the DigiPolice by stealing their secret Digimon. She activates it, unleashing a Brigadramon.

Brigadramon aims its attacks at Eiji, Satsuki still wanting to kill him, but Marvin has Chaosdramon shield him. This was enough to pin Chaosdramon down, and with only Airdramon left — Numemon/Satsuki charge in to try and free Ryudamon. Eiji and Marvin are shocked to learn the DigiPolice had a Mega level Digimon the entire time, with Satsuki faking annoyance that Chaosdramon's Red Digizoid was able to withstand its attacks. With Brigadramon in range, Chaodramon grabs its arms but Satsuki reveals she wanted this to happen and had tricked him since it had missile launchers in its claws and as such would now be able to fire all of them at Chaosdramon at point blank range. Before it can do so, Eiji yells at them to stop fighting as "it" was here. Omegamon of the Royal Knights had arrived.

Omegamon attacks Kosuke, but Marvin is able to have Chaosdramon block the attack. As it falls to the powerful Royal Knight's attack, it is able to launch one final attack itself but Omegamon avoids it. Satsuki has Brigadramon attack Omegamon, though its attacks do little to it. Though she had no desire to help the SoC, she continues to have Brigadramon attack the Royal Knight as she didn't want Omegamon to kill Ryudamon/Yulin alongside the others. Brigadramon overheats, with it now unable to continue fighting. Omegamon comes out of the smoke unharmed, with there now being nothing to stop it killing Kosuke. The hacking was at 97%, and as Omegamon charged at Kosuke the mission seemed like it was going to fail. Kosuke however, reveals he had a trump card — and pulls out two Digimon Docks. He summons two Mega level Digimon and has them block Omegamon's attacks. With the hacking now at 99%, the gateway scans the three Prototype Digimon with its analysis bringing up holograms of their Ultimate forms. This confirmed they met the requirements, with the gateway giving Kosuke the key. The hacking was complete. Omegamon kills Kosuke's Mega Digimon but it is unable to reach the group in time as upon Kosuke activating the key — he, Eiji, and the Prototype Digimon vanish. Sons of Chaos: Seekers Chapter 4-5

Kosuke and the others find themselves in a void beyond the Gateway, with Eiji wondering if they had managed to reach the depths of the Digital World. As the Hackers and their partners discuss their surroundings, Kosuke pulls up a monitor — and after searching it informs the group they were in the Source Domain. Upon that realization, Yulin and Ryudamon wake up — with Kosuke giving a quick update on what had happened. Yulin is enraged, but is unable to do anything as Ryudamon was still restrained. Kosuke apologizes for doing so, and tells her he had no choice as he had to do the hack. She asks what happened to Satsuki, and is surprised to learn she had stolen Brigadramon. As the two talk, Eiji expresses shock at the fact Kosuke and Yulin actually knew other by name — the leader of the DigiPolice and the leader of the Sons of Chaos. Figuring there was no point in keeping secrets, Kosuke tells Eiji a brief story about the duo's time working with Tomonori Ryusenji back when they were students. With how long the conversation had gotten, Eiji asks if they can really stand around and do this since Omegamon could come for them at any moment. Dorumon alleviates his fears though, telling him that only Prototype Digimon could be in the Source Domain — and as such, Omegamon couldn't get in. It even states that King Drasil wasn't allowed in. Eiji breathes a sign of relief, though goes back to worrying when Dorumon says it actually has no idea if the Royal Knights were allowed in or not and was simply theorizing. As Kosuke states that they had finally reached the place where they could get the Sacred Chalice, Loogamon notices the nearby area's smell as changed. As it sniffs it more, the area Loogamon was sniffing changes shape. Sons of Chaos: Seekers Chapter 4-6

As Loogmon and Eiji react in fear at the changes, Loogamon realizes it had seen the newly formed object before — it was the same device in Tomonori's office that displayed Vaccine, Virus, and Data. The three orbs on it, one for each Attribute, envelop the three Prototype Digimon, with it confirming the trio match the requirements. Now all Kosuke had to do was hack into the source code of the system so he could get access to the Sacred Chalice. Phase 3 of Operation Tartarus was now complete, with Phase 4 now beginning.

As Eiji watched Kosuke hack, he realized that Tomonori had given him Loogamon and told him to infiltrate the Sons of Chaos all for this moment — so that he could digivolve Loogamon to the Ultimate level and help Kosuke free Saya. Yulin continues to try and break Ryudamon free from the restraints so that she could stop Kosuke from hacking into the Digital World, but still found herself unable to do so. As Kosuke states he would hack into the system, slipping passed King Drasil and the Royal Knights, Yulin continues to try and break free as she didn't want her former friend to become a target of the Royal Knights. She also didn't want him to upset the balance between humans and Digimon, just to free one human as the risk of the Digimon retaliating against the Human World was too strong. Kosuke insists it will all be worth it to save Saya, his fiancée and the Professor's daughter, this fact shocking Eiji since he wasn't aware of Saya's connection to Kosuke — never mind the Professor. This finally had Eiji realize just how important she was to Kosuke and Tomonori. Not actually caring about Saya, Loogamon tells Kosuke to hurry up as it was only interested in saving Leon and Pulsemon. Yulin tries to reason with Eiji, hoping he can put a stop to what was happening, but he and Loogamon tell her they had come too far to turn back now. Kosuke continues his hack, with the Attribute logos connecting together followed by lots of objects coming out of the ground — eventually forming a stone circle around the group. Dorumon and Loogamon, Loogamon pulling the restrained Ryudamon, approach the newly formed altar with the now woken Ryudamon telling them they can do what they want as they had bested it in combat. Dorumon states it will pay back the love Kosuke had given it by helping free Saya, but not just that — it would free the Digital World and change it.

Eiji asks Kosuke if he knew how to find Pulsemon's data, to which he states he doesn't as he only had the information for Saya's BlackAgumon. Loogamon points out it remembers Pulsemons scent, feeling that'd be enough, whilst Eiji pulled out the medicine he was given by Tomonori to cure someone of DMIA. As Loogamon sends the scent data over to Kosuke, Yulin reacts in shock having learned Tomonori was part of the operation. As Kosuke continues to hack, letters only the Prototype Digimon would understand appear with the trio decoding it. Kosuke's monitor suddenly shuts off however, ending the hack, with Tomonori arriving and greeting the group with a cheery "good morning". Sons of Chaos: Seekers Chapter 4-7

Everyone is confused by Tomonori's presence, which the professor fails to understand, as he is the one who asked them to raise the Prototype Digimon for him. Tomonori then restrains Loogamon and Dorumon with the same tool used on Ryudamon, bypassing both of their security systems. Loogamon realizes the restraint tool was installed in them from the start. Tomonori states the restraint tool is part of the research tools installed in the Digimon handled by Ryusenji Electronics and the Digimon Linker. Eiji realizes the Digimon Linker's monitoring of his health and Loogamon's progress is all being sent to DDL. Tomonori reveals he can forcibly take control of their Digimon whenever he wants, even when they are mindlinked, and that their Partner Digimon are his tools.

Yulin realizes that while the Prototype Digimon are meant to access the Source Domain, the Digimon Linkers are meant to be a bridge between the Real World and Digital World, granting Tomonori access to the Source Domain. Eiji realizes Tomonori's image is a video feed projected from their Digimon instead of being properly hololized. Loogamon regains its memory of being captured by DDL employees in the Wall Slum and having the restraint tool installed in it. Kosuke angrily reacts to Tomonori's actions. Tomonori starts to decrypt the Data part of the Source Domain's code with Dorumon's interface and states it's only right the leading expert on Digital World research be the one to do this. Kosuke gets angry because they were supposed to be on the same side, and he also wants to save Saya. Eiji asks Tomonori about Saya, trying to learn the full story.

Tomonori explains how he covered up the accident with the Tartarus probe to protect Kosuke and Yulin, and his promise to look after them even after they left Ryusenji Electronics. He also tells Kosuke and Yulin he's proud of having invested so much in them, and asks them to see his current actions as him calling back the favor they own him. Eiji continues his question, realizing it makes no sense for Tomonori to fight Kosuke if they are both trying to save Saya. Tomonori reveals he has no interest in looking for BlackAgumon, which confuses Eiji. Yulin asks Tomonori about a hunch she has had. Tomonori calls the universal directory information tree and summons an unconscious Pulsemon to the Source Domain, revealing one can easily search any Digimon by their identification code in the Depths of the Digital World.

Tomonori then summons BlackAgumon, also unconscious. The professor confirms his suspicion that a Partner Digimon survives their mindlinker's death. His words shock all in the room. Tomonori shows for a brief moment a video of Saya in a capsule full of colored fluid, revealing the videos he had been sending to Kosuke were fake, and Saya has been dead for a long time. Sons of Chaos: Seekers Chapter 4-8

Kosuke refuses to believe it, with Tomonori finding Kosuke's reaction boring — since he had predicted that's how he would react. He did find satisfaction in the fact the fake hope that she was alive allowed him to control Kosuke though, since it had allowed him to achieve his goals. Eiji yells out to Kosuke that they had found the BlackAgumon the Sons of Chaos had been looking for, with this snapping Kosuke back to reality. Still refusing to believe she was dead, he takes out the medicine that would sever her and her BlackAgumon's Mindlink connection. Tomonori tells Kosuke that the medicine was real, and would indeed work, and that the only thing he had lied about was the fact she had already died but asks him if he would be able to live with the consequences — what would happen if her consciousness had no body to return to? As he looked at the BlackAgumon, he found himself unable to administer the medicine. He didn't have it in him to find out if Tomonori was lying or not.

Tomonori's hacking finishes, with Dorumon screaming in pain — the pain causing it to pass out. Kosuke apologizes to his partner, with Tomonori telling the group they had no idea what Kosuke was going to do with the source domain once he had it. Kosuke tells Tomonori he hadn't needed to do any of this as he was simply going to give the credit to him anyway — since he only cared about Saya — though Tomonori didn't care as he was done with Kosuke. He would turn his attention to Ryudamon, and begin hacking it just like he had done to Dorumon moments before. Yulin asks Tomonori why he was doing this — since his daughter was dead — with Tomonori telling the group he was interested in the Source Digimon. Yulin tells him that trying to find it was too dangerous, to which he agrees, but had no desire to stop in his goals despite how dangerous it could be as it would satiate his boredom. Yulin tells him she had lost all respect for him, whilst Eiji declares him a traitor. Tomonori didn't care though, and tells them he was going to Mindlink with the Source Digimon.

Tomonori asks Eiji how he had betrayed him, to which Eiji changes his mind and decides he actually hadn't. He realizes that someone as talented and rich as Tomonori would never take interest in someone like Eiji unless it was to have him digivolve Loogamon, and so couldn't betray him as he was never really on Eiji's side in the first place. Tomonori tells him that he was the perfect candidate to raise Loogamon, since his entire family were dead and his DS levels with Loogamon were high and that had he told him about the plan — neither he nor Loogamon would've developed as well as they had. Seeing that Eiji had understood what had happened, he became confused as to why he had taken the side of Kosuke and Yulin. As Tomonori questions Eiji, Loogamon gets up and tells Tomonori to shut up. Having heard enough, Loogamon asks why Tomonori hadn't put a stop to its digivolution to Helloogarmon — since he had clearly been watching the battle — with Tomonori telling that watching the battle was more fun that stopping it, even had it resulted in Leon's death. This enraged the duo further, with Tomonori disappointed that they had supposedly betrayed him. He tells them that Leon knew his secret and had grown too strong — and so had to be dealt with.

Eiji and Loogamon still had the desire to save Leon and Pulsemon. Their hearts become one, with this allowing Loogamon to break free from the restraints. This shocks Tomonori, with Loogamon telling him that it can delete any foreign objects within its body with its flames. Tomonori pauses his hack on Ryudamon, and turns his attention to Loogamon. Eiji readies his Digimon Linker, and tells Tomonori that this wasn't going to end well for him. Sons of Chaos: Seekers Chapter 4-9

Tomonori had already hacked Dorumon, and, having paused his hacking of Ryudamon to hack Loogamon instead, tries to using his hacking tools to restrain it so that he could do so. As Eiji wonders how they would be able to stop him, since they couldn't attack a hologram, Loogamon tells its partner that the battle would most likely be against Tomonori's pawns. As he says that, Dorumon — having woken up during the conversation — attacks Loogamon. Eiji asks Kosuke why he had told Dorumon to attack them, though Kosuke — who had not been paying attention to what was going on as he was still wallowing in despair — looks at the commotion and asks why Dorumon was attacking them. This has Eiji realize Kosuke wasn't behind it, with him coming to the conclusion that someone else must've been controlling its actions. He asks Tomonori if he was the one doing it, to which he confirms he was as he had hacked into Kosuke's Mindlink — allowing him direct control of Dorumon's actions. He forces Dorumon to digivolve, with Dorumon digivolving all the way to the Mega level.

With Dorugoramon by his side, Tomonori asks Eiji if he was going to fight him or if he was going to join his side and allow him to complete the hack of the three Prototype Digimon. He tells him that if he helps him get access to the Source Digimon he would forgive his betrayal and would allow him to continue working for him. He states he would give him a free apartment, as much food as he wanted, and that if he took this offer one of the women working for him might fall in love with him — specifically naming Hatsune. He gives him to the count of ten to make his choice, with Eiji actually considering accepting since he could skip university and work for such a prestigious company and maybe even become one of the higher ups or use the money to make his own business. As it seems he was going to accept the deal, Loogamon reacts in shock, with Eiji explaining that he had already had a taste of the good life and wanted more. Tomonori reacts happily, and tells Eiji he will make sure he has a high salary, though Eiji reveals he was bluffing and instead was going to forge his own path by using the Digital World to bring people to together. Not amused by the deception, Tomonori gives him one last chance to reconsider but Eiji refuses and has Loogamon digivolve.

Soloogarmon attacks Dorugoramon, but its attack does nothing to its Mega level opponent. Tomonori sarcastically congratulates the duo on their attack. Yulin tells Eiji about Dorugoramon's attacks, and that it is very effective in both short and long range combat — with this leaving very little in the way of defeating it. Eiji is surprised upon hearing Yulin helping him, though she quickly points out the fact that Soloogarmon would lose from just one attack. Refusing that notion, Eiji and Soloogarmon declare they'll win and start mocking Tomonori. He sees through their ruse though, and tells them that since he isn't Mindlinking they wouldn't be able to stall him out and that all that would happen is that Kosuke would fall into DMIA — since Kosuke was actually the one Mindlinking with Dorugoramon. Even if that were to happen, Tomonori would still have control of Dorugoramon. Their plan thwarted, Soloogarmon uses its thrusters to fly into the air — in the hopes that it would be be able to avoid Dorugoramon's attacks and defeat it from the air. As Soloogarmon avoided the attacks, they notice Dorugoramon had suddenly stopped paying attention to them and realize it was now aiming its attack at Ryudamon and the others. Eiji was confused, since killing Ryudamon would make accessing the Source Digimon impossible, and realizes his actual target was Pulsemon. He was going to use Pulsemon as a hostage to get what he wanted. Not wanting his friend to die, Soloogarmon changes from aerial attacks to a direct attack but is easily defeated by Dorugoramon at close range. Tomonori tells Eiji he is lucky that he can't kill Soloogarmon, since he still needed it, and mocks the death of Eiji's parents. This further angers Eiji, with Tomonori telling him he had won since no matter what he did he still had Pulsemon. Tomonori motions to Pulsemon but reacts in shock when he sees that it, BlackAgumon, and Ryudamon were no longer there. One of Eiji's Tyrannomon arrives, with Tomonori realizing he had had his Tyrannomon do stuff whilst Tomonori was distracted with Soloogarmon. As Tomonori wonders where they had gone, he figures there was only one place they could be — the altar. Eiji and Soloogarmon try to tell the Tyrannomon to flee but they're too late, with Dorugoramon getting there within seconds. Dorogoramon attacks the Tyrannomon at the altar, though Soloogarmon is able to get there in time and block the attack — saving its allies. Tomonori becomes confused, since Eiji could easily replace the Tyrannomon, but Soloogarmon tells him to leave its friends out of their battle. Now even more determined to win, Eiji and Soloogarmon's hearts become even more linked — and with an even higher desire to save their friends — Soloogarmon digivolves to Fenriloogamon. Sons of Chaos: Seekers Chapter 4-10

Eiji and Tomonori have a back and forth about their ideals, with Eiji declaring he would take Tomonori out. Tomonori tries to bribe Eiji again, but it fails once again after Loogamon snaps Eiji out nearly falling for it again. The talking over, Fenriloogamon attacks the mind controlled Dorugoramon.

Two of Eiji's Tyrannomon take the Mindlinked Yulin/Ryudamon, Pulsemon, and BlackAgumon to the nearby stone circles, with the third limping there having taken damage from Dorugoramon's previous attack. The group now safe, Yulin watches the battle between the two Mega level Digimon from afar. Kosuke Kisakata's hololized hologram had hitched a ride on the back of the injured Tyrannomon. He apologizes to Yulin, then approaches BlackAgumon with the syringe he hadn't been brave enough to use on it, wanting to put an end to the years of his life dedicated to saving his fiancée. Rather than use it though, he ends up just telling "Saya" how her father had taken everything from him. Yulin tries to comfort him, then tells him to watch with her to see what Eiji and Fenriloogamon could do. As they watch the battle between the two Mega level Digimon, Yulin and Kosuke praise Eiji for all he had achieved despite the many setbacks in his life — as well as how strong his resolve was to save his friends. Figuring he still had one more thing left to do, Kosuke uses the syringe on Pulsemon.

Pulsemon runs into battle, and joins Fenriloogamon's side. As the battle continues, Tomonori starts to hack, reminding the duo he had gained access to the source code, and as he does, Kosuke's hologram collapses. Yulin freaks out, confused as to what was going on, with Eiji and Leon/Kazuchimon noticing something was happening to Dorugoramon's DigiCore. Large amounts of data begins to pour into Dorugoramon's DigiCore via its interface, with everyone realizing that if it continued — Dorugoramon would die as its body would be unable to handle that much data. Wanting to save Dorugoramon, the two Mega Digimon try to attack it — but are too late. Dorugoramon, in a bid not to die, began Death-X-evolution. Sons of Chaos: Seekers Chapter 4-11

He then watches as Eiji and Leon and defeat DexDorugoramon, reverting it back to Dorumon. As they see the threat had been dealt with, they also notice Tomonori had left. Kosuke arrives and declares that Phase Four of Operation Tartarus was now complete since they had secured BlackAgumon. BlackAgumon and Kosuke thank Eiji for all he had done, though they have to cut it short when Eiji has Fenriloogamon Takemikazuchi revert to Loogamon and Pulsemon then cuts the Mindlink as he had ran out of time. Sons of Chaos: Seekers Chapter 4-12 Epilogue

Afterwards, everyone agrees to not say a word about what happened, though most of the information ended up leaking anyway. Over the next year, having found BlackAgumon, Kosuke does little very work with the SoC — with this ending up causing Eiji to be seen as the unofficial leader by the members themselves.

Eiji invites Kosuke to his birthday party at a yakitori restaurant, though figures he wont be able to join since he was in a different country. This wound up not mattering though, as Kosuke mindlinked with Dorugoramon and travelled to the Wall Slums. They found everyone's partner Digimon having their own party; with it, Kosuke, and BlackAgumon joining in. Kosuke asking where Eiji was and Loogamon tells him he was on his way. As they wait — they do a toast. As they toast, Eiji and the others arrive. Epilogue

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