Chapter 121

Second Semester Opening Ceremony (後期始業式) is the one hundredth and twenty-first chapter of Kohei Horikoshi's My Hero Academia.

Summary
Toshinori Yagi regrets having brought the secret of One For All upon Katsuki and apologizes. Toshinori decides to properly explain to Katsuki about everything regarding One For All. And so, Toshinori spoke to Katsuki about One For All being a transferable Quirk that is passed down from generation to generation in order to fight evil, how he became the Symbol of Peace using One For All, the injury that limited him to using One For All and how he chose Izuku as his successor. After hearing the truth about One For All from Toshinori, Katsuki chastises Izuku for blabbering about One For All. Toshinori tells Katsuki that using up all his power against All For One was his choice and he does not need to bear any responsibility. Having heard everything, Katsuki decides that he is going to rise higher than Izuku as a hero; Izuku accepts Katsuki's challenge and will rise higher than him. As Izuku and Katsuki argue about them rising higher than one another, Toshinori is happy to see that Izuku and Katsuki have become proper, true rivals. The secret of One For All has become a secret amongst Toshinori, Izuku, and Katsuki.

Afterwards, Shota Aizawa helps bandage Izuku and Katsuki's wounds and then proceeds to wrap them up using Capturing Weapon as punishment for fighting. It is revealed that Toshinori was the one who stopped Shouta from interfering with Izuku and Katsuki's fight after telling him that he would handle them and would bring them to him afterwards. After Toshinori tells Shota that the fight was brought about due to Katsuki feeling guilty about his retirement, Shota still refuses to let Izuku and Katsuki's transgression of fighting go by and will give an appropriate punishment after finding out who started the fight first. Katsuki says that he threw the first punch while Izuku retaliated. Shota punishes Izuku and Katsuki by placing them under house arrest; Izuku three days and Katsuki four days. During their house arrest, Shota states that they will be cleaning the dormitory common spaces day and night and they must write a written statement of regret. Shouta tells them that if their injuries do not heal they must go to the infirmary and they must not dare think about relying on Chiyo Shuzenji. Having criticized them enough, Shota tells them to go to bed.

The next day, Class 1-A learn about Izuku and Katsuki's fight. As Izuku and Katsuki clean the dormitory. Ochaco hopes that they made up, to which Izuku replies that their reconciliation is hard to put into words; Tenya is happy that they got off the hook with house arrest only and that the rest of Class 1-A will attend the opening ceremony without them. Shoto asks Katsuki what he plans to do about the Provisional Hero License Supplementary lessons, to which Katsuki tells him that it is none of his business. As they clean, Katsuki talks to Izuku about his One For All Shoot Style, telling Izuku that his wind up motions are too big and are not useful in a slugfest and that the style does not mix well with punches. Izuku is glad about the information.

Outside, Tenya tells Class 1-A not to break formation. While on their way, Neito Monoma criticizes Class 1-A for having two of their classmates fail. Eijirou Kirishima wonders if any of Class 1-B failed, to which Neito laughs. Neito reveals that all of Class 1-B passed and none of them failed. Class 1-B are happy that they have pulled ahead. Shoto Todoroki apologizes for letting Class 1-A down, but Eijirou tells Shouto not to let it bother him. Pony Tsunotori informs Class 1-A that according to Sekijiro Kan, during the Second Semester Classes 1-A and 1-B will be having a class together. Denki Kaminari comments on Pony being a foreigner; Pony responds in a negative way, courtesy of Neito's bad teaching, causing Itsuka to criticize Neito. Someone tells Class 1-A and 1-B to stop holding up the line; Tenya apologizes for doing so. The person is revealed to be Hitoshi Shinso. As Hitoshi passes by, Hanta Sero comments on Hitoshi being more serious.

All of U.A. arrive at Ground Beta. Nezu introduces himself. After talking about his diet and lifestyle going out of sync, he states that the reason for his lifestyle becoming inadequate is due to the incident that took during the summer break. He talks about All Might's retirement and the negative effect it will have on society and the Department of Heroics will likely see the most striking affects. Nezu tells the Second and Third years that the Hero Internships that they are engaged with they must have an awareness of the crisis and conduct themselves accordingly. Nezu apologizes for bringing down the mood but the heroes are dealing with the situation to the best of their abilities and he would like nothing more than to develop them into individuals who will take over their efforts. Nezu ends his speech by saying that whether they are in the Departments of Heroics, Support, and General Education and even the staff of U.A., they must not forget that they are the successors to the hero society.

After Nezu leaves the podium, Toshinori ponders about "successors" and thinks back to when Nezu made a suggestion to look for a successor at U.A. and gave him the opportunity to look for a successor by taking up a teaching position at U.A. Toshinori looks into the crowd of U.A. students while thinking about Nezu stating that there is someone who would surely be a fitting successor amongst the U.A. students.