Aizetsu is a tall young adult man with a lean muscular build and shoulder-length hair and narrow, deep blue eyes. He has two prominent curved horns on his forehead and cracked markings under his eyes. Aizetsu also has the kanji for "sorrow" etched into his tongue. As a demon, Aizetsu has pointed ears and sharp nails on each finger. He is usually seen wearing a dejected expression on his face. Aizetsu wears a black kimono with white lines running through various areas of the clothing.