Muzan Kibutsuji

Regeneration: Muzan can continue to live even if his body or head is completely destroyed.

Extrasensory perception: Kibutsuji is able to sense the presence of other demons or someone's thirst for blood.

Absorption: Muzan can devour other demons or objects.

Biological manipulation. Muzan can change his body, enlarge his limbs, change his body size, etc.

Immortality: After taking a medicine called "Blue Spider Lily", Muzan can live indefinitely and also becomes immune to diseases.

Curse: Muzan can control the bodies of demons.

Poison Resistance: His body is much more resistant to the poison from wisteria, which is fatal to normal demons.

While Muzan was still in his mother's womb, his heart stopped several times. He was born without a pulse and did not breathe, which is why he was considered stillborn, and only let out his first cry when he was about to be cremated.

One day, a demon hunter who possessed the breath of the sun almost killed Muzan, but the man survived and henceforth became more careful with all people who possessed or could possess this breath. The distinguishing feature of these people were hanafuda earrings.

Muzan later decides to create a group of twelve of the strongest demons, dubbing them the "Twelve Demon Moons" for his potential protection and uniting them with two goals: eliminating all demon hunters and also finding his treasured cure.

When Muzan was a young man, he was diagnosed with a disease that would cause him to die before he reached the age of 20. The doctor treating Muzan gave him a prototype of a cure, but Muzan, angry that his condition was getting worse, killed his doctor. He later realized that the cure actually worked, and his body became stronger. It was easy for him to eat people to survive, but he faced another problem: he could not be in the sun. Because sunlight was now deadly to him, Muzan was forced to live a nocturnal lifestyle, which made him very angry. At this point, he deeply regretted killing the doctor before he finished developing the cure, called the "blue spider lily." Muzan searched all over the country for the spider lily, which was part of the cure, but could not find it, so he began to create more demons. He wanted to spread demons throughout the world, hoping that one of them would eventually be able to defeat the sun, or at least find the blue spider lily, so that Muzan could become a perfect being.

About 400 years before the manga's plot, Muzan met Tamayo, who was ill. Muzan turned her into a demon.

When he is not hiding behind a facade, his malice and overflowing violent intent are so incredibly evil that they can be perceived by others. In particular, Yoriichi Tsugikuni described him as boiling magma erupting from a volcano, ready to devour everything.

To prove this, he curses his subordinates in a horrific manner so that none of them will utter his name, or they will be immediately killed in a painfully brutal manner. Interestingly, this almost paranoid sense of self-preservation contrasts with his delusions of grandeur.

Furthermore, his delusional sense of omnipotence is such that he compares himself to natural disasters, namely, things that are far beyond what a person can compare to and fight against. As a result, he believes that the Demon Slayers are a group of deviants who are unable to accept the natural order of things and regain normalcy when other people simply move on after a tragedy. His analogy is indicative of a complete inability to feel empathy or remorse for his actions, given that none of the murders he has ever committed (directly or indirectly) have been the result of accidents, but carefully planned acts of pure evil.

He has shown himself to be quite manipulative and cunning, able to fit in well in human society, even having his own family. His long life and continuous practice have allowed him to take on many roles in society and play them wisely, including children and women if he chooses. This life has also given him great intelligence and the ability to think tactically. Muzan is a clever strategist, able to deal with adverse situations quickly and quite well, although this may also be because losing his subordinates means nothing to him in the long run.

Muzan is ruthless and tries to bring his every plan to perfection. He does not forgive the Moons for incompetence and failures, but can praise them for successfully completing a mission. Kibutsuji does not take his enemies seriously. Muzan also does not like being asked questions or given orders. He is prone to narcissism.

His inflated ego and delusional sense of self-importance are so great that he cannot tolerate 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 drunk men simply for being rude to him, and killed their companion even though she did nothing, all while proclaiming his own perfection and superiority over them. When he finally confronted Kagaya Ubuyashiki, the man responded to Muzan with a tone of pity and sadness for the life he had led. In Muzan's mind, this was registered only as insults and threats, which he used to justify his hatred of Humanity and the Demon Slayers.

Due to his apparent superiority and two-faced nature, he feels little affection for his minions, using and discarding them as disposable pawns as he pleases. He does not allow his subordinates to question his will, regularly using brutal repression. Many of his subordinates, in turn, deeply fear him and watch their words and thoughts carefully, afraid to say anything that might upset him. They cannot even dare to think anything that might be perceived as hostile by Muzan, as he is able to read the minds of all the Moons. He is able to sway many demons to his side with promises of power, revenge, and greatness so 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 fed for him. Unfortunately, all of these promises are ultimately false, given that Kibutsuji only cares about himself and has no qualms about killing his own people to protect his own safety.

Muzan appears to be a twenty-year-old man. He has wavy black hair and red eyes. Muzan dresses very extravagantly, and most often it is a white shirt, a black jacket, white pants, a white tie, and black shoes with a small heel. In the manga, he is shown to be able to change his appearance.