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. During his meeting with the Lower Ranks, he disguised as an elegant woman wearing a long black yukata Blood Demon art is Biokinesis to shapeshift, he's cold-hearted, ruthless, intimidating, smart.