Muzan Kibutsuji is the demon king and overall the strongest demon in Demon Slayer, being the main antagonist. Muzan is a tall man with a lean muscular build, pale skin complexion, curly black hair and sharp, almond-shaped eyes. Cat-like irises in plum red color, sharp blue nails and in his twenties. wearing a white fedora, embroidered black tuxedo, white tie over a black dress shirt,white dress pants and black loafers. Blood Demon art is Biokinesis. cold-hearted, ruthless, intimidating, smart. 