Katsuki is a crude, arrogant, short-tempered, and aggressive person, especially at the beginning of the series. Katsuki tends to come off as unheroic; this problematic behavior going all the way back to his early childhood days when he was known to bully a young, Quirkless, Izuku Midoriya. However, after being accepted into U.A. and experiencing several personal defeats, one of them even coming from Izuku, Katsuki has gradually changed into a less antagonistic person.