It's About Your Quirk is the one hundredth and seventeenth chapter of Kohei Horikoshi's Boku no Hero Academia Manga.
Summary
While the rest of Class 1-A are asleep, Katsuki takes Izuku to Ground Beta, the site of the Battle Trial where he and Izuku fought for the first time. Katsuki remembers the time where Izuku was a Quirkless good for nothing and then suddenly out of thin air he manifested a Quirk and by some miracle he was accepted into U.A. Eventually, Izuku received his Provisional Hero License while he failed. Izuku tells Katsuki that he received his Provisional Hero License for performing well, but Katsuki orders him to keep quiet and let him finish. Ever since the Kamino Incident, Katsuki has been putting the pieces together and has been thinking about it the whole time; Izuku is fully aware as to what Katsuki has discovered. Katsuki states that Izuku received his Quirk from All Might. Having witnessed All For One's ability to steal Quirks and bestow them onto others as well as figuring out that All Might is an acquaintance of All For One, Katsuki hypothesized that All Might also has some form of Quirk transference because he has become weaker ever since coming to U.A and meeting with Izuku. Seeing that Izuku isn't denying anything, Katsuki knows that he is right about Izuku gaining All Might's Quirk.
Izuku knows that Katsuki is correct about him getting his Quirk from All Might and this is his punishment for trying to reveal his Quirk to Katsuki. Izuku asks Katsuki how knowing the truth about his Quirk is going to help him. Katsuki knows that he and Izuku has always looked up to All Might and seeing the person who he thought was a pebble on the side of the road being acknowledged by the person he looks up to is why Izuku is going to fight him here and now.
Izuku is shocked that they have to fight and thinks that they should fight during practice. Katsuki tells Izuku that they cannot fight in a class session as the teachers will prevent them from going all out. Katsuki wants to fight Izuku to find confirm what is great about him and why All Might would go so far to help Izuku. Katsuki wants to find out that if Izuku's aspirations are greater than his because he is beginning to doubt if his own aspirations were wrong the whole time. Katsuki charges forward, but Izuku uses One For All Full Cowl to quickly dodge Katsuki's explosion. However, Katsuki's explosion still manages to hurt Izuku's leg. Katsuki comments on Izuku's analytic skills while Izuku is surprised that they are actually going to fight.
List of Characters in Order of Appearance
Izuku
Katsuki
ground Beta