Katsu Ki is a young man of average height, with ash blond, Spiky hair and red eyes. At school, He wears the standard U.A. Uniform save for the customary red tie. Underneath his blazer, he wears a white button-up shirt with the first couple buttons undone. Despite wearing a belt along with the uniform's green pants, Katsuki does not pull them up all the way, giving his pants a baggy appearance.