Kibutsuji Muzan

He has proven himself to be quite manipulative and cunning, able to blend in well with human society, even having his own family. His long life and constant practice have allowed him to assume many roles in society and play them wisely, including children and women if he so chooses. This life has also given him great intellect and the ability to think tactically. Muzan is a clever strategist, capable of quickly and effectively handling adverse situations, although this may also be because the loss of subordinates means nothing to him in the long run. Due to his apparent superiority and two-faced nature, he feels little affection for his minions, using and discarding them as disposable pawns whenever he pleases. He does not allow his subordinates to question his will, regularly employing brutal repression. Many of his subordinates, in turn, deeply fear him and carefully guard their words and thoughts, afraid to say anything that might upset him. They can't even dare think anything that Muzan might perceive as hostile, so capable is he of reading the minds of all the Moons. He is able to sway many demons to his side with promises of power, revenge, and greatness as long as they serve him. His intellect and manipulation shine here, as many find these promises quite appealing, as he encounters many of his subordinates at their lowest point, when their emotions are easily exploited. Alas, all these promises are ultimately false, given that Kibutsuji cares only for himself and has no qualms about killing his own people to protect his own safety. When he's not hiding behind a facade, his malice and overflowing violent intent are so incredibly vicious that they can be perceived by others. To prove this, he curses his subordinates in a terrifying manner.

Muzan is ruthless and strives to perfect every plan. He doesn't forgive the Lower Moons for incompetence and failure, but he can praise them for successfully completing a mission. Kibutsuji doesn't take his enemies seriously. Muzan also dislikes being questioned or given orders. He has a tendency toward narcissism. It's also not hard to guess that Rui was one of Muzan's favorites, as he no longer saw any point in keeping all the Lower Moons and killed them all after Muzan's death. This has its reasons: Rui, unlike other demons, was loyal to Muzan and actively killed demon hunters. His inflated ego and delusional sense of self-worth are so great that he can't stand being mocked or corrected, believing that others exist only to serve him. This also means he rarely takes any opponent or threat seriously. He brutally murdered a pair of drunken men simply for being rude to him, and killed their companion when she did nothing, all while proclaiming his own perfection and superiority over them. When he finally managed to confront Kagaya Ubuyashiki, the man responded to Muzan with a tone of pity and sorrow for the life he had led. In Muzan's mind, these were registered only as insults and threats, which he used to justify his hatred of humanity and the Demon Slayers. Furthermore, his delusional sense of omnipotence is such that he compares himself to natural disasters, namely, to that which far exceeds what a human can compare to and combat. Demon Slayers are a group of deviants who cannot accept the natural order of things and regain normal lives when other people simply move on after tragedy. His analogy reveals a complete inability to feel empathy or remorse for his actions.

He appears to be a twenty-year-old man. He has wavy black hair and red eyes. Muzan dresses rather extravagantly and wears a white hat with a red ribbon.