Yukio Oikawa is a man of formidable height, with pale skin and dark hair and eyes. After his friend Hiroki dies and while Myotismon resides in his body, he bears a more ghastly visage, with light grey skin, no eyebrows, and very small pupils.
As a child, he wore his hair short with bangs combed to the side. In middle school, he wore a uniform consisting of a black gakuran-style jacket with gold buttons over a white undershirt and black trousers.
As an adult, he wears his hair parted in the middle. At the age of 25, he is shown wearing a dark turtleneck sweater and light-colored pants.
By December 2002, he has grown out his hair to his shoulders. He wears a long purple trenchcoat with black lines and grey fastenings over a red dress shirt, a dark grey tie, dark green trousers and brown and black dress shoes.
As a child, Yukio Oikawa was very lonely, and couldn't find a single person who understood him. In middle school, he met a boy named Hiroki Hida, who became his only friend.
When both Hiroki and Yukio were young, they somehow managed to tap into the Digital World through a video game, and became obsessed with the fact they could talk to the creatures within it. They both ended up communicating with the Digital World for hours and hours on end through their video games. Hiroki's father, Chikara, became very worried about the obsession the two boys seemed to have. When he felt that things had gone far enough, he forbade his son from playing video games and tried to separate Hiroki from Yukio, fearing that they were spending too much time together and that Yukio was a bad influence. Though the two were heartbroken, they remained close friends. They made a promise to each other that, one day, they would go to the Digital World together. The two continued to fantasize and share their dreams about the Digital World together through adulthood, never sharing their secret with anyone else.
In adulthood, Oikawa worked with Ken Ichijouji's father as a geneticist, while Hiroki became a police officer and started a family. The two continued to study the Digital World long after their contact with it was cut; in 1995, when the Highton View Terrace incident occurred, Oikawa went to investigate and worked alongside Nancy Takaishi, T.K.'s mother. There, Oikawa learned that Highton View Terrace served as a gateway to the Digital World.
In 1999, Hiroki took a bullet for an important political figure in London and died from his wounds. Oikawa was utterly devastated by the death of Hiroki, his only friend, and became embittered that Hiroki had in a sense "broken" their promise by no longer being there to fulfill it.
On August 3, 1999, Oikawa was present in Tokyo Harbor when the DigiDestined defeated Myotismon. Seeing the Digital World in the sky, Oikawa held up a framed picture of Hiroki to the sky while crying that Hiroki is unable to see their dream realized. At that time, Oikawa sees the DigiDestined returning to the Digital World and yells for the children to take him with them. It was at that moment of grief and weakness that Oikawa was soon possessed by the disembodied spirit of Myotismon after being promised to be taken to the Digital World.
Following the possession, having no memory of it, Oikawa became darker in demeanor and appearance as his obsession with the Digital World grew increasingly unhealthy. Despite not being consciously aware of the evil entity he was hosting in his body and influencing his actions, Oikawa combined his knowledge as a geneticist and knowledge gained from Myotismon to create Digimon to serve him. Combining data with his own DNA, he created Arukenimon and Mummymon with the purpose of having them do his bidding, and in some way sending a part of himself to the Digital World. But while they could travel to the Digital World, he still could not, and seeing his creations freely wandering the Digital World only made him yearn to be there even more. He soon came to the conclusion that he would have to weaken the boundaries between the worlds to accomplish this. When he saw Ken Ichijouji at the funeral of the boy's older brother and sensed the Dark Spore residing in his neck, he manipulated Ken into becoming the Digimon Emperor.
As the Digimon Emperor, Ken constructed Control Spires which began to weaken the boundaries and upset the balance of the many worlds. But when the DigiDestined defeated the Digimon Emperor and Ken was reverted to his old self, they began demolishing the towers. Oikawa knew he would have to take action, and sent Arukenimon and Mummymon to battle against the DigiDestined and complete the Emperor's work. Arukenimon and Mummymon's plan of having BlackWarGreymon, one of Arukenimon's creations, destroy the Destiny Stones almost succeeded, but was thwarted at the last minute by Azulongmon. Following this, Oikawa decided it would be easier to weaken the barrier from his own side.
Oikawa instructed Arukenimon to open the Digital Gates in the entire world. During Christmas day, the Japanese DigiDestined traveled around the world and helped close the gates, Arukenimon and Mummymon drove around Tokyo in a truck and kidnapped twenty children. The following day, they kidnapped Ken as well, so that Oikawa could scan his Dark Spore and pass it on to the children. After this, Oikawa, Arukenimon and Mummymon ran off to hide in a vacation house near Mt. Fuji, but BlackWarGreymon came from the Digital World to destroy them. BlackWarGreymon sensed that Arukenimon and Mummymon were not natural Digimon, which Oikawa confirmed. He also sensed that Oikawa belonged to neither world, due to Myotismon's spirit. Oikawa received unlikely help from the Chosen Children, as they knew they might need him to take the Dark Spores out of the children. As BlackWarGreymon battled WarGreymon and Imperialdramon Fighter Mode Oikawa and his henchmen fled and returned to Oikawa's run-down apartment in Tokyo.
The next day, he confronted Cody Hida, knowing he was a DigiDestined, but unaware that he was Hiroki's son. However, when he saw the name Hida on Cody's bag, he realized that the boy was the son of his best friend and fled. That night, he visited Hiroki's grave, plagued by memories and guilt. He didn't let this stop him, however, and went on to absorb the power of the Dark Spore of Noriko Kawada, whose Spore blossomed earlier than expected. He succeeded in this despite the DigiDestined's attempts to stop him. Unexpectedly, Chikara, Cody's grandfather and kendo instructor, happened upon them. Remembering Oikawa as his late son's childhood friend, Chikara tried to reason with Oikawa, explaining that they both missed Hiroki and he needn't be alone in his grief. Chikara almost succeeded in emotionally reaching the anguishing Oikawa, however, Myotismon interfered, using the power he absorbed from the flower to gain brief control over Oikawa's body, and tried to kill the old man. BlackWarGreymon intercepted the attack, but in the process was mortally injured, catching a glimpse of, to his horror, the shadow of Myotismon. While everyone stood shocked by BlackWarGreymon's actions, Arukenimon and Mummymon took the chance to pull Oikawa away from the scene. BlackWarGreymon, now aware that Oikawa was being used as a puppet, flew into the sky and used the last of his power to seal the Highton View Terrace gate to the Digital World.
After the other Dark Spores had grown strong enough to bloom into flowers, Oikawa gathered all of the children together in Highton View Terrace and used the Dark Spores to try and open a gate to the Digital World. However, he did not know that BlackWarGreymon had sealed the gate with the last of his power. Myotismon sensed this, and made Oikawa open up a portal to an entirely different world, the world of dreams. He entered the portal along with the Dark Spore children, his henchmen and the younger DigiDestined, who made it through the portal at the last second. Oikawa was confused when he realized he didn't reach the Digital World, and Myotismon's spirit used the powers of the dream world to remind Oikawa that he had possessed him. Following this, Oikawa fell to his knees in pain and the spirit of Myotismon separated from his body and assumed his appearance before absorbing the Dark Spores of the children to complete his rebirth as MaloMyotismon.
The departure of Myotismon from his body left Oikawa with barely any life for himself, but he was able to witness the final battle between all of the DigiDestined from around the world against MaloMyotismon. After the evil Digimon was finally defeated, Cody went back to the World of Dreams through the rip that was created in the barrier between the worlds, and tried to bring Oikawa to the Digital World. Thanks to his best friend's son, he finally got an actual glimpse Digital World, and met the Digimon he had seen so long ago in the video game he once played with Hiroki, Datirimon, who joyfully announced that he was Oikawa's partner Digimon. Unfortunately, Oikawa's body was so badly weakened that despite being only inches away, he was unable to enter the world that he so badly aspired to reach. Knowing that he had little time left to live, Oikawa sincerely apologized to the DigiDestined for what he had done, and expressed regret that he'd never allowed himself to open up to others, as it was part of the reason he'd become such a miserable person and was so easily exploited. He then proceeded to use the power of the world of dreams to repair the damaged Digital World with his own being, changing his dying body and soul into data (shown in the form of a swarm of glowing iridescent butterflies). His spirit lives on as a part of the Digital World itself.
After the Digital World is highly damaged by the battle against MaloMyotismon, Oikawa uses the power of the world of dreams to convert his body into energy to restore the Digital World, in the form of a swarm of butterflies. Twenty five years later, the butterflies fly past the DigiDestined's children.
Notes and references