Tensei Ida/Synopsis

History
At some point before Tenya attended U.A. High, he asked his older brother what motivated him to be a Hero, to which Tensei replied that he wanted to be a 'cool' type of Hero that helps others when they are in need. When Tenya speaks of his admiration for his older brother, Tensei is joyful that Tenya looks up to him and says that he must be a great Hero since Tenya admires him.

Vigilante - My Hero Academia: Illegals
Tensei and his hero agency Team Idaten are dispatched to the Naruhata district highway for reports of a runner-type villain whose Quirk is amplified by Trigger. While Tensei is initially able to catch up to the villain, he fails to match with the villain's greater range of mobility, for which the villain mockingly states that the Turbo Hero must stake his life on running if he wants to catch him. The villain effortlessly avoids Tensei's attempt to subdue him and attacks, causing Tensei to crash due to his high speed. An airbag system prevents the crash from being fatal.

Later, Tensei meets with Koichi Haimawari during a morning jog. At the time, Koichi is fully aware of the law preventing the use of Quirks in daily life and decides to practice early in the morning to avoid authorities. Instead of arresting Koichi, Tensei takes an interest in his mobility-type Quirk and even offers him advice, apparently solving one of Koichi's biggest faults when using his Quirk. Impressed by Koichi and his Quirk, Tensei happily offers him a business card to Team Idaten, assuring him that even an unlicensed hero such as Koichi could find a place on his team.

Later, Tensei and Team Idaten are again tasked with capturing the runner-type villain, who notes that Tensei seems to be making sharper movements. Tensei made the decision earlier to sacrifice all the safety measures of his suit (much to his team's disapproval), in order to shed as much weight as possible and match the villain in his mobility. The villain believes he has successfully convinced Tensei to foolishly risk his life to keep up with him, but Tensei makes clear that he did not merely endanger himself to keep pace; instead, he is trusting that his team will keep him safe.

Tensei and his team devise a strategy in which Tensei would lure the villain into a dead-end strip of the highway, with the rest of Team Idaten ready to apprehend the villain when he falls into their trap. While Tensei is kept safe thanks to the crash pads his team laid out for him, the villain avoids the trap entirely when he reveals he has wings and the ability of flight. The villain then escapes from the highway and takes to an old part of the Higashi-Naruhata district, all while avoiding Team Idaten's coordinated attempts to corner and subdue him. Tensei remarks the difficulty of the operation is due to the town's unfamiliar layout and the villain's ability to use the shadows to his advantage.

Later in the chase, Tensei and his team unexpectedly find the villain beaten and subdued, all thanks to the efforts of the vigilantes Knuckleduster and The Crawler. Koichi claims that being used to the old district's layout makes it easy to determine the villain's likely escape route.

The next morning, Tensei races to meet with Koichi during his morning jog in order to thank him, having recognized him from the night before. Though Koichi is terrified of having his identity revealed, Tensei says that the vigilante's secret identity is safe with him. Tensei then requests the return of his business card, claiming that Koichi has already found his place as "The Crawler", and he respects him for it. Much to Koichi's dissatisfaction, he returns the card, to which Tensei makes the attempt to cheer up his jogging buddy with a friendly race.

Sometime later, in a meeting with Eraserhead, Best Jeanist, Manual, Death Arms, Snipe, 13, Endeavor, Air Jet, Midnight, and Gunhead, a police officer speaks about the unwilling civilians injected with Trigger. The officer explains that the people in question were more victims than they were villains. Endeavor argues that any public use of a quirk is illegal and that they should treat them as villains and let the police investigate the backgrounds of future captures. He said this is the only way to protect the innocent while not risking themselves by hesitating every time they see a new enemy. All Might, who was not present, had his reply to the problem delivered by Naomasa. He stated that he would assess the situation at the scene more carefully because as heroes they must not bring harm to innocent citizens. This was in direct opposition to Endeavor's answer, greatly angering him. After the meeting ended, a Suicide Bomber attacked the police station. Before Ingenium or Best Jeanist could react, Endeavor took action. Endeavor, still fuming over what had just transpired, decided he was going to incinerate the villain. However, the villains' quirk would most likely have a volatile reaction to Endeavor's quirk. Midnight calls Aizawa to help resolve the problem before it gets explosive. Aizawa wraps the villain up throwing him into Midnight. By this point, she has undone her blouse revealing her chest. Suicide Bomb then lands face first in her breasts, no longer angry, and passes out. The Midnight Boys come bursting in asking if Midnight is unharmed. She tells them to hand the villain over to police custody. She tells Bomb if he acts up again she will personally bring him to her agency and dole out punishment. Bomb is clearly not upset by this but the Midnight boys become increasingly jealous.

Unforeseen Simulation Joint Arc
Tensei is first mentioned by his younger brother, Tenya Iida, when Ochaco Uraraka asks about his lineage. Tenya discloses that the Iida Family have been heroes for generations and asks if Ochaco or Izuku Midoriya know of the Pro-Hero Ingenium. When Izuku confirms that he is a fan of Ingenium's, Tenya reveals that the Turbo Hero is his brother. Tenya also mentions that Ingenium is a leader with dozens of sidekicks working alongside him and he wishes to become just like his older brother.

U.A. Sports Festival Arc
Tensei searches the streets of Hosu, Tokyo for the Hero Killer "Stain". While ordering his sidekicks to patrol certain areas, Tensei happens to notice Stain in an alleyway and confronts him. The Hero Killer defeats and grievously injures Tensei before leaving him for dead. The police find Tensei in a pool of his own blood and take him to the Hosu General Hospital. Once there, Tensei undergoes an operation that saves his life. Tenya eventually makes his way to see Tensei at the Hospital. In spite of his injured state, Tensei apologizes to his younger brother for not being the hero he looks up to anymore. Tensei also admits that he has become paralyzed from the waist down, marking the end for the Turbo Hero "Ingenium". Tenya cries out and pleads for Ingenium not to die, so Tensei decides to pass the moniker down to his younger brother.

Joint Training Arc
Tenya mentions that his brother has been recovering remarkably since the Hero Killer incident. Tensei later appears in Tenya's flashback during the third round of match-ups against Class 1-B. He teaches Tenya how to improve his Quirk and make Recipro more powerful, faster, and last longer than before.