The Suspicious Travel Guide! Navimon I Am!

Navigation apps go haywire as Haru grows into his new role.

Summary
On October 7 at 7:42 PM in Success Academy, Takeru "Watson" Wato is playing a video game with his friends when the security guard tells them to head home otherwise they'll turn off the Wi-Fi. They realize how late it is, so Watson uses an app to determine the fastest route home, though his friends are dubious about the route chosen. The app leads Watson down a winding route, eventually sending him down a narrow alley, at which point, obviously infected, emerges, and Watson screams.

The following day at 6:44 AM at Haru's Home, Haru and wake up. Gatchmon enthusiastically observes the breakfast Haru's mother made for Haru, which leads into a day of exploration for the pair. They end up at Ai Kashiki's house, which doubles as a bookstore, and are met by Yuujin Oozora. Ai isn't present, though a thoroughly beaten-up Watson is. Watson tells his story about the previous night. At the other end of the narrow alley was a ferocious dog who attacked him. Ai's father comes across them as Watson complains about his navigation app, and then he realizes that Ai hasn't returned from her errand, and she's not answering her phone. Haru realizes that it's most likely the work of a virus infected an Appmon.

He and Gatchmon head out to search, with Yuujin and Watson following. Yuujin praises Haru for his initiative before splitting off with Watson. As they search, Gatchmon explains that Appmon are monsters associated with smartphone apps, and that they have been going berserk due to the L-Virus released by a malignant AI seeking to spread chaos in the human world. Gatchmon himself was investigating it before meeting Haru. He then gives the AI a name: Leviathan. At that moment, Gatchmon freezes up, and when he manages to start again, he realizes that it seems like even remembering Leviathan causes him to freeze. The entire time, they both are being watched through cameras.

Their conversation is interrupted by a deliveryman apologizing for the delay, as his navigation app has led him astray. They discover Navimon inside of it, who calls himself "Navimon Hattori" before escaping. The pair give chase as Gatchmon scans Navimon, pegging him as the source of everyone's current woes with navigation apps. Yuujin calls Haru to tell him that they've found Ai, who had been led astray by a navigation app, and that he could return. Navimon then challenges them and enters an AR Field. Though Haru is hesitant about fighting, he follows at Gatchmon's prompting.

Haru appliarises Gatchmon. Navimon tags him with an navigation arrow, which allows him to use homing attacks. Using Deep Search, Gatchmon searches for a weakness and comes up with the term "rotation". Gatchmon then tells Haru to applink him with, which allows him to wield Messemon's power. Gatchmon then rotates with Messemon's ethereal body trailing behind him, which renders Navimon unable to target him. He then attacks Navimon with Messemon's attack, stunning him long enough to defeat him. Navimon is then purified of the L-Virus, and Haru obtains Navimon's Appmon Chip. then reveals himself before announcing that he will erase them. He takes photos of himself as he attacks, and before Haru and Gatchmon can perform a weakness search, he blinds Gatchmon with a flash. Haru realizes Navimon's powers could help, so he applinks him to Gatchmon but ends up appfusing them into instead.