Diavolo has layered, red hair with his bangs parted to the left side, tan/dark skin (depending on his form), and pale golden eyes. Like the seven Avatars of Sin, he too has painted nails - black, in his case. Unlike the other Devildom students, Diavolo wears a special red RAD Uniform with a blue ribbon accent. He pairs it with a formal black shirt with gold button-down collars as well as a neat white tie with a tiepin underneath.