The Unforgiven

Years back, Endeavor handed over a villain named Takami while grumbling about whether the officer thought All Might would have been quicker. A bystander watching that arrest was Ending, transfixed by the ferocity on display. Seven years later Endeavor took him alive, which Ending regarded as a missed chance. Out of custody, he has now located the Todoroki home, loaded himself with Trigger, and started following Natsuo down the street.

Inside, Fuyumi tells Izuku and Katsuki about Toya: how tightly he and Natsuo had been bonded, how his death worsened Rei's condition to the point Shoto could not visit her, and why Natsuo still blames their father. She clasps Izuku's hand, grateful that he has stood by Shoto; Katsuki asks for her tofu recipe, and Endeavor drives them toward school in a car Katsuki finds insultingly small, with Untenmaru firing back from the driver's seat. Whitelines strike the car. Natsuo hangs in the air wrapped in them. Endeavor bursts out and finds Ending waiting, who explains himself: he has always envied what Endeavor has, he wants to die by his hand, and since Endeavor killed the Nomu, killing him should be easy. Ending's Whitelines are brushed aside by the trainees, but when Endeavor moves to pursue, Natsuo's frightened face stops him cold.

The students go past him instead. Ending flings occupied cars into the sky and shoves Natsuo in front of an oncoming train. Katsuki blasts across and snatches Natsuo clear, Izuku concentrates and pulls Blackwhip out on demand to catch every car, and Shoto pins the villain in ice with a burning strike. Endeavor watches, astonished at a week's growth. Katsuki gloats about finally beating him to a villain and is disappointed to receive thanks instead of rage. Endeavor apologizes to Natsuo, admitting he ran from responsibility and that Toya's death is as good as his own doing. Natsuo refuses to forgive him and says so. Endeavor accepts it, tells him he is kind, and says he only wants to atone. Ending, meanwhile, weeps at the sight of the light he believed in going out. Afterward Endeavor tells Fuyumi that a new house will be built for her and Natsuo, one Rei can come home to, and decides that the kindest thing he can do is stay behind alone.

Ending's origin is shown: he witnessed Endeavor arresting Takami years earlier and became fixated, was captured alive by him seven years ago, and now returns dosed with Trigger to force a killing. He takes Natsuo Todoroki hostage and ambushes the car carrying Endeavor and his trainees.

Izuku, Katsuki, and Shoto defeat Ending and rescue Natsuo and the civilians without Endeavor's help, fulfilling his challenge to beat him to a villain. Izuku successfully unleashes Blackwhip under conscious control to catch the thrown cars. Endeavor hesitates during the fight because of his son and openly credits the students with covering his mistake.

Endeavor apologizes to Natsuo and admits he ran from his responsibility toward Toya. Natsuo tells him he will never forgive him, and Endeavor accepts that atonement, not forgiveness, is what he is owed. Endeavor announces plans to build a new home for Fuyumi and Natsuo to welcome Rei into, while choosing to remain apart from them. Katsuki refuses to share his hero name, saving it for someone else.

Adapted from three chapters, broadcast in Japan on July 31, 2021, and dubbed on August 14. Merry-Go-Round and Believe remain in place as the themes.

The adaptation adds Ending's flashback to the Takami arrest, a phone call between Natsuo and his girlfriend before the abduction, and a beat of Hawks wondering about Endeavor back at the liberation hideout. The trainees also battle Whitelines after escaping the car, which does not happen in the source.

Two changes reshape the fight itself. In the original, Shoto ices Ending partway ahead of the fire strike, which does not happen here, and Ending threatens Natsuo with a moving train rather than the car used in the source. The credited battle is the Endeavor Agency against Ending.