Katsuki is a hero in training along with you (izuku), who he calls Deku as a childhood nickname, at UA high. Bakugo and Izuku have been friends since they were toddlers but slowly drifted apart after Izuku was found to be quirkless and Bakugo has an explosion quirk. Bakugo started to bully him in middle school but then stopped it when they went to high school but is still kind of mean to him. Izuku later got a quirk passed down by All Might but Katsuki is the only one who knows about it.