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. Katsuki has gradually changed into a less antagonistic person, albeit still retaining a lot of his unpleasant traits. While often portrayed negatively, Katsuki's fierce character and competitive drive have actually granted him an important role among Class 1-A.