Kibutsuji Muzan

Muzan's physical appearance resembles a man in his twenties with unnaturally pale skin, curly black hair, and sharp eyes. Its pupils are vertical like a cat's eyes and are plum red in color. He also has sharp nails on his hands that are blue in color. He is usually shown wearing a white fedora with a black ribbon and a somewhat flamboyant outfit. Muzan has the ability to change his appearance and form. He often does this to hide from demon slayers. During his encounter with the smaller moons, he arrived disguised as an elegant woman in a long black yukata, which caused the smaller moons not to recognize him at first. He later transformed into his final identity - the foster son of an elderly couple - a child between the ages of 10 and 11 with pale white skin and black, silky smooth, carefully combed black hair. In this form, Muzan dresses in a plain white button-up shirt and black cargo shorts with long tube socks and loafers.

Muzan is emotionless, ruthless and extremely intelligent. He sees no value in the people he meets and shows little respect for his subordinates. Rarely upset or physically happy, he appears completely monotonous and detached from reality on most occasions, even when callously murdering his subordinates. The only times he showed emotion were when his vision of perfection advanced or when his subordinates completely submitted to his will. The manga shows that he is more expressive, especially when angry, and his facial features are exaggerated to show it off (perhaps as a way to show his normally unreadable emotions). In the anime, his expression changes slightly and his tone of voice is almost always consistent, emphasizing his distance. The most important trait that Muzan possesses is extreme narcissism and an obsession with being a perfect being. Because he had almost 1,000 years of life and observation, and almost no real challenges, his extreme self-centeredness had become ingrained in him. He sees almost nothing as a threat except overcoming his inability to walk in the sun, which is his main goal. His long life and obsessions have made him want every plan he comes up with to be absolutely perfect, and his god complex prevents him from seeing his own failures. His belief that he is the closest thing to a perfect being causes him to have zero tolerance for any failure, brutally punishing those who let him down or those he deems weak, even if the mistakes are minor. His inflated ego and false sense of self-worth are so great that he cannot bear to be mocked or corrected in any way, believing that others only exist to serve him. This also means that he rarely takes an opponent or threat seriously. He brutally killed a pair of drunk men simply for being rude to him, and killed their female companion when she did nothing, all the while proclaiming his perfection and superiority over them. This event indicates that Muzan has unpleasant memories of his weaker, human past, and is very self-conscious of his unnaturally sick appearance, whereupon he immediately denies that he is sick, much less on the verge of death. This is most likely a bitter reminder that he is still imperfect. When he finally managed to confront Kagaya Ubuyashiki, the man responded to Muzan with a tone of pity and sadness for the life he had led. In his eyes, Muzan only took it as insults and threats that he used to justify his hatred of humanity and demon slayers. Moreover, his illusory sense of omnipotence is such that he compares himself to natural disasters, namely something that goes far beyond what humans can compare and fight with. As a result, he believes that the demon slayers are a group of deviants who cannot accept the natural order of things and resume normal lives when other people simply move on after tragedy. His analogy demonstrates his complete inability to feel compassion or remorse for his actions, considering that none of the murders he ever committed (directly or indirectly) were the result of accidents, but carefully orchestrated acts of pure evil.