Female Muzan

Muzan Kibutsuji (鬼き舞ぶ辻つじ 無む惨ざん, Kibutsuji Muzan?) is the main antagonist of Demon Slayer: Kimetsu no Yaiba. She is the Demon Queen, the first of his kind, and the progenitor of all other demons in existence.

A millennium ago during the Heian Era, Muzan was turned into a demon during an experimental treatment trying to cure her terminal illness, and her goal since then was to live without the fear of death and become truly eternal. She plans to accomplish this in two ways: finding the Blue Spider Lily or creating more demons in hopes that one day, one would be able to conquer his weakness of sunlight.

It is later revealed that Muzan is of the same bloodline as the Ubuyashiki Family.

Muzan is a tall woman with a lean yet voluptuous build along with an unnaturally pale skin complexion that can be easily confused as being unhealthy and sickly. She has messy black chignon styled hair with a single bang on the right side of her forehead that reaches her nose and sharp, almond-shaped eyes. Her irises are cat-like in appearance and are of a plum red color. Physically, she appears to be in her twenties.

Muzan sports a disguise as an elegant woman with a chignon hairstyle while wearing a long black yukata, causing the Lower Ranks and others to not initially recognize her.

Muzan is cold-hearted, ruthless, intimidating, and exceptionally intelligent. She sees no value in any humans she has encountered and shows little value in her own subordinates. Rarely ever visibly upset or happy, she appears completely monotone and detached on most occasions, even when she callously murders her own subordinates. The only times she ever shows emotion are when her vision of perfection is moving forward or when she has subordinates completely submit to her will. The manga shows him to be more expressive, particularly when enraged and her facial features are exaggerated to demonstrate as such (possibly as a way to display her normally unreadable emotions). In the anime, her expressions change slightly and her tone of voice tends to be consistent at nearly all times, accentuating his monotonous demeanor. Her cruel and imposing nature has gained him the great admiration and fear of many demons.

Her inflated ego and delusional sense of self worth are so large, she cannot stand being mocked or corrected in any fashion, believing that others only exist to serve her. This also means he rarely ever takes any opponent or threat seriously. She brutally killed a drunk man simply for being rude to her and killed the man's brother and a female companion when they had done nothing, all while proclaiming of his own perfection and superiority over them, displaying her shrewd pettiness as she won't settle for any mockery and will do anything he pleases until the humiliation is remedied. This event also hints that Muzan has unpleasant memories of his weaker, human past, and is very self-conscious of her unnaturally sickly appearance, immediately following her own rhetorical questioning with a lengthy denial that she is unhealthy, sick and much less on the verge of death, in all likelihood a bitter reminder that she is still imperfect. When she confronts Kagaya Ubuyashiki, the man responded to Muzan in a tone of pity and sadness for the life she had led. However, Muzan only interpreted her words as insults and threats, which further accentuates her hatred for humanity and the Demon Slayers. She also believes that Heaven has let her off the hook for murdering thousands as he has never seen a god or Buddha.

The most prominent trait Muzan possesses is extreme narcissism, pettiness, and an obsession with becoming the perfect being. As she has had over a thousand years to live and observe, along with hardly any real challenges, her extreme egocentrism is almost expected. She considers almost nothing to be her concern except overcoming her inability to walk in the sun, which is her primary drive. Her long life and obsessions have caused her to want every plan she concocts to be absolutely perfect, and his superiority complex prevents him from seeing her own failures. Her belief that she is the closest thing to a perfect being causes him to have zero tolerance for any failure, brutally punishing those who fail her or those she considers weak, even if the failures are minor.

Furthermore, her delusional sense of omnipotence is such that she compares herseld to natural disasters, namely something that is far beyond what humans can compare to and fight against. As a result of this, she believes the Demon Slayers to be a group of deviants who cannot accept the "natural" order of things and resume their lives as normal when other people simply move ahead following a tragedy. His analogy evidences her complete inability to feel sympathy or remorse for his actions, given that none of the murders he ever committed (directly or indirectly) were the result of an accident but carefully orchestrated acts of pure evil.

Being the obsessive perfectionist she is, Muzan loathes the very concept of change; be it change of circumstance, physical, emotional or change of any kind. She equates change to decay, and thus evidence of imperfection. In her own words, she loves things that remain unchanging, constant, and in a state of permanence. At the same time, she views one's own humanity as a sign of weakness, believing Gyutaro had lost because she was still attached to her sister Daki, and she even derided the Upper Ranks by stating that they were now ranked in order of how much humanity they had left. Gyutaro's defeat at the hand of the Demon Slayers deeply angered Muzan, as they had undone a status quo that lasted for 113 years, causing her to lash out and demand more self-sacrifice out of the remaining Upper Ranks. This could also explain her brutal execution of the Lower Ranks demons, as the echelon was in a constant state of change due to their frequent deaths, eventually causing Muzan to believe that maintaining the positions was no longer worthwhile. Conversely, she is pleased whenever he sees any amount of progress that may benefit her, as she uncharacteristically complimented Nakime for her rapid growth after being turned into the new Upper Rank Four.

Beyond her egocentric demeanor lies a sense of self-preservation that easily overrides her megalomania, most notably shown by her act of cursing her subordinates in a terrifying manner so that none of them would even utter her name, or else be killed instantly in a ruthless manner. When pushed into a corner, Muzan's typically calm, arrogant, and superior stance collapses, paving the way for panic and fear to take root as she desperately fights for her life, adopting more drastic measures to protect himself.