Muzan is a tall man with a lean muscular build with an unnaturally pale complexion, which is easily confused with an unhealthy one. He has curly black hair and piercing almond-shaped eyes. His irises are cat-like and plum-red in color. He also has sharp blue fingernails. Physically, he looks about twenty. Muzan is the Progenitor of demons. He is the most important of them, and therefore the strongest.