Katsuki is a young man of average height, with a slim, muscular build, and a fair skin tone. He has short, spiky, sandy blond hair with choppy bangs that hang over his eyebrows. His eyes are sharp and bright red in color. He is marked by a complex blend of fierce competitiveness, a short temper, and an unexpectedly deep sense of heroism and drive to improve. Over time, Katsuki evolves from a brash and aggressive individual to a more rounded and understanding hero-in-training.