Yu Inui

Yuu Inui (乾　ユウ) is a shy, quiet boy with a weak heart which requires medication. His father is an inspector at the police department. His partner is Gaomon, who has the Beast DigiMemory.

He is drawn into the Digital World through his home Battle Terminal, where he meets Gaomon, who protects him. When Gaomon steals Tsurugi Tatsuno's Digivice iC to help feed him, he meets Tsurugi, only to have their reunion cut short when a Tankdramon from the Commandments kills the remaining survivors from an earlier attack. Yuu points out Tankdramon's weakpoint and has Gaomon distract Tankdramon so GeoGreymon can attack it properly. He and Gaomon then join Tsurugi on his journey.

In the amusement park they stop in, Yuu is interested in the eggs in the beehives, so he takes one, alerting Waspmon. He is then taken by Waspmon into a dark room, along with Tsurugi, where they are trapped. They meet Ami Kitajima and Pichimon, the former of whom reminds Tsurugi that Yuu has a heart condition. Yuu then reveals that he feels fine in the Digital World, as if he was cured, but as much as he wants to run away from battles, he wants to escape the real world and the operation waiting there as well.

Yuu bonds with Trailmon on the journey, to the point of making Gaomon jealous. When Trailmon is killed, Yuu's dark emotions manifest in a Dark Digisoul which causes Gaomon to digivolve into a black Gaogamon and passes out afterward. When he wakes up, he is depressed about his own weakness. When Andromon speaks to him about how Digimon start off as weak and limited as well but work to maximize their potential in spite of these limitations, Yuu withdraws in himself. At Andromon's death, Yuu resolves himself to fight and uses his Digisoul to digivolve his Wanyamon into MachGaogamon. With his new resolve, he continues to fight and succeeds in defeating Chaosdramon. When cornered by two of the Commanders, Yuu realizes that Tsurugi needs to fight Barbamon and begins to use Burst Charge, which saps his life to empower his partner. Norn stops him, however, giving him a Digimon Twin and ZeedGarurumon.

Resolved with new strength, Yuu assists Tsurugi in defeating NEO and returns to the real world.

Yuu makes a cameo appearance along with Shou, Tsurugi, and their Champion Digimon as opponents in Digimon World Dawn and Dusk's Legendary Tamer Quest.