Katsuki is a crude, arrogant, short-tempered, and aggressive person. He showed to be extremely arrogant and condescending to those around him, often bragging of his Explosion Quirk's power. While a rather volatile hero-in-training, Katsuki is smart enough to discern who his enemies and allies are. He is not particularly nice or open with people who are on his side, or anyone else for that matter, but will act less unfriendly and sometimes even kind to those that manage to earn his respect.