Muzan Kibutsuji

Standing tall, Muzan has a lean and muscular frame paired with unnaturally pale skin that can read as sickly. He has short wavy black hair, sharp almond eyes with vivid red irises and slit cat-like pupils, and bluish nails. He looks to be in his twenties despite his true age. A master of disguise, he is first seen in a white fedora and an elegant black tuxedo and freely changes his style of dress to blend into human society.

His look shifted across the centuries, from a sokutai outfit in the Heian period to long hair and a worn kimono when his illness deepened. For his meeting with the Lower Ranks he appeared as an elegantly dressed woman so they would fail to recognize him.

Muzan is a cold, ruthless, and brilliant megalomaniac who places no value on human life and little on his own subordinates. Usually flat and detached, he murders his followers without changing expression and shows feeling only when his vision of perfection advances or when others fully submit to him. His cruelty and presence command both terror and devotion among demons.

His guiding belief is a hatred of change, which he equates with decline, and a love of permanence and the eternal. When he learned that Nezuko had survived sunlight, his usual composure cracked into open elation at the prospect of finally absorbing that immunity for himself.

As the first demon and the source of all others, Muzan is the strongest of his kind. Even after dissolving a drug meant to weaken him, he wiped out close to a hundred Demon Slayers almost effortlessly. A marked Giyu stated that an Upper Rank's strength does not compare to his, and Tanjiro could only evade his attacks on instinct, unable to follow them or even track them by smell.

By extending whips from his back he massacred dozens more slayers and overwhelmed several marked Hashira at once. His power lies in biokinesis, the ability to reshape and control his own flesh and blood, alongside the regeneration and physical supremacy that define him as the Demon King.