Episode 13.5

Episode 0 is a recap episode of the My Hero Academia anime. This episode summarizes the events that occurred in the first season, from Izuku Midoriya's meeting with All Might up to the end of Class 1-A's Rescue Trial class.

Summary
A young Izuku Midoriya stands up to Katsuki Bakugou, in order to defend another child from being bullied. Katsuki mocks him for being Quirkless and attempting to play hero.

Izuku is a huge fan of the world's greatest Hero, All Might who is known as the Symbol of Peace and wants to be just like him, but is later told by a doctor to give up: he has two joints in his pinky toe, which shows that he is Quirkless. At middle school, Katsuki mocks Izuku for trying to enroll at U.A and uses his Quirk, Explosion to destroy his notebook on Heroes. On his way home, Izuku runs into a slime-like villain but is saved by the timely arrival of All Might. Izuku clings onto All Might, causing him to land on the rooftop of a building. Izuku asks All Might if someone who doesn't have a Quirk could also be a hero like him. Suddenly, All Might reverts back to his normal form, much to Izuku's shock. All Might explains that a run in with a powerful villain has left him badly wounded and limited his Quirk usage. All Might tells Izuku that its fine to dream, but he shouldn't let his dreams blind the reality he is in.

Izuku walks back home, sulking about All Might's words. In an alley, Izuku sees that the slime-like villain has escaped and has taken control of Katsuki Bakugou, causing chaos with Katsuki's Explosions. Izuku rushes to save Katsuki, much to All Might's shock. As Izuku struggles trying to save Katsuki, All Might transforms into his Hero form and defeats the slime-like villain with Detroit Smash. Later on, All Might explains to Izuku that he was inspired by Izuku's Heroism and was wrong about what he said to him. All Might tells Izuku that he can become a Hero, causing Izuku to cry because the person who told him this was none other than his favorite Hero.

All Might reveals that his Quirk is One For All which can be passed down like a torch and has elected Izuku as his successor because he has been searching for a successor for a long time and has shown to be an ideal candidate. For 10 months in order to inherit One For All, Izuku goes through All Might tough training regimen. On the day of U.A's Entrance Exam, Izuku has become a fine vessel and receives One For Al from All Might by ingesting a piece of his hair.

During the Entrance Exam, Izuku is unable to earn any points until a giant robot is released and is about to trample on an examinee named Ochako Uraraka. Izuku uses One For All for the first time and delivers a powerful punch to the giant robot, which destroys it. Back at home, Izuku thinks he failed, but All Might tells Izuku that the Entrance Exam wasn't just testing the examinees' abilities to destroy robots, but their ability to rescue others as well. Because Izuku rescued Ochako, it earned him enough points to enroll into U.A. All might congratulates Izuku and welcomes him to his Hero Academia; U.A.

Izuku becomes a part of Class 1-A, which his childhood friend Katsuki Bakugou is also a part of. His homeroom teacher is Shouta Aizawa, a strict man with high expectations. Shouta has Class 1-A partake in a Quirk Apprehension Test in order to gauge their Quirks' abilities. After being lectured by Shouta during the ball throw test, Izuku takes control of One For All and uses it on his finger at the last second, allowing him not only to launch the ball at a high speed but to mitigate the damage as well. Shouta is impressed while Kastsuki is furious that Izuku has been hiding a Quirk from him all along.

Izuku's next class is the Battle Trial, in which Class 1-A is divided into Hero and Villain teams respectively. Izuku is paired with Ochako Uraraka as part of the Hero team and faces off against Katsuki Bakugou and Tenya Iida. Izuku and Katsuki battle one another, but Izuku is overwhelmed with ease, Izuku uses One For All again during his battle against Katsuki, but uses it on the ceiling of the building in order to distract Tenya allowing Ochako to retrieve the bomb, giving him and Ochako the victory.

Afterwards, Class 1-A take a trip to the Unforseen Simulation Joint, a place that simulates natural disasters among other types of disasters in order to practice rescuing. Suddenly, the USJ is attacked by a group of villain called the League of Villains lead by a man known as Tomura Shigaraki and have blocked all communications; their mission is to kill All Might. Shouta, No.13 and Class 1-A fight against the League of Villains. Surprisingly, Class 1-A manage to defeat most of the villains and protect themselves but Shouta and No. 13 are defeated by Noumu and Kurogiri respectively. Before Tomura and Noumu can lay their hands on Izuku and Tsuyu, All Might arrives to save the day.

All Might engages Noumu in a viscous battle in which Tomura reveals his intentions to prove that the Symbol of Peace is a sham and that Heroes are no different than villains. Eventually, All Might defeats Noumu with a devastating blow. Before Tomura and Kurogiri can finish what Noumu started, they are repelled by the arrival of U.A's teachers, courtesy of Tenya.Tomura and Kurogiri are sucked into No. 13's Black Hole, but Kurogiri teleports Tomura and himself back to their hideout at the last second.

Class 1-A are mostly uninjured except for Izuku while Shouta, No. 13 and All Might are being treated by Recovery Girl. At the end of the day, Izuku prepares himself for U.A's next event, the Sports Festival.