Muzan Kibutsuji, the first demon of Demon Slayer

He walks through the Asakusa crowd with a woman on his arm and a little girl by the hand. No one notices him. Tanjiro, however, smells a scent no human carries, and realises in an instant that he has just crossed paths with the murderer of his family.

Muzan Kibutsuji is not a monster lurking at the back of a cave. He is an elegant man who rents houses, marries, takes his children for walks and changes identity when the previous one starts to draw attention. This portrait traces his origin, the exact reason for his fear of daylight, the way he makes his demons and the night when the Hashira of the Demon Slayer Corps finally corner him. The whole camp he built is presented on our page about the demons of Demon Slayer and the demon Moons.

Who is Muzan Kibutsuji?

In Demon Slayer, Muzan is the origin of everything. Every demon Tanjiro encounters, from the most wretched devourer of travellers to Upper Moon One, carries a share of his blood. Killing him would not mean eliminating one more enemy: it would put an end to the entire species.

His appearance varies over the course of Demon Slayer. Embroidered black suit and pale hat in the streets of Asakusa, a woman in a dark yukata before his Lower Moons, a sickly ten-year-old boy in a family that has adopted him. The only constant is his overly pale skin, which a drunk passer-by points out to him one evening, before dying for that remark.

The Demon Slayer character seeks neither power nor domination of Japan. He wants only one thing, and he repeats it for a thousand years: to walk in the sun without burning. Everything else, the demons created by the hundred, the Twelve Moons, the hunt for the Kamado family, serves only that goal.

His other dominant trait is a total intolerance of failure. He reads the thoughts of those who approach him, executes a subordinate for an ill-judged thought, and regards his own demons as replaceable equipment.

This embroidered black suit is his best-known outfit, and you will find it among the demon outfits. You will find everything the shop offers in his name in the collection devoted to Muzan Kibutsuji.

The doomed child and the Heian-era doctor

Muzan is born in the early 900s, at the end of the Heian era, almost a thousand years before the period in which Demon Slayer takes place. His heart stops several times before his birth. He is declared stillborn, carried off to be cremated, and starts crying on the way.

His childhood confirms the diagnosis. A doctor announces that he will not live past twenty and gives him a remedy of his own making, still at the trial stage. Weeks go by, his condition worsens, and Muzan kills the doctor in a fit of rage.

The remedy was working. He realises it a few days later, in a new body, fast, that no longer knows pain. The price appears at the same time: he must eat human flesh to keep going, and daylight reduces him to ashes.

The treatment was to be completed with a flower, the blue spider lily, which the doctor grew. Muzan spends the next thousand years looking for it without finding it, and our article on the flower Muzan searched for a thousand years explains why this quest was doomed from the start.

Why does the sun burn him?

The weakness to the sun is not a vampire convention borrowed lightly: it is the direct consequence of the unfinished treatment. The remedy rebuilt Muzan’s cells by making them dependent on human flesh, and light destroys that structure instantly.

All the demons of Demon Slayer inherit this flaw, since they inherit his blood. Only one creature escapes it, and that is precisely what triggers the end of the story: Nezuko Kamado, whose transformation is detailed on our page about Tanjiro’s sister and her resistance to daylight.

From the moment Hantengu reports to him that Nezuko can stand in broad daylight, Muzan abandons the search for the flower. His new priority becomes capturing the young demon girl, whose body holds the solution he has been pursuing since the Heian era.

How does Muzan make demons?

In Demon Slayer, the method comes down to one gesture: Muzan injects his blood into a human, through a finger pushed into the skin. Most bodies cannot withstand the dose and dissolve. Those that hold out wake up starving, regenerate their limbs and lose all control of themselves.

The amount of blood determines the strength of the result. A passer-by transformed in an alley remains a street demon. A chosen fighter receives an enormous concentration and becomes an Upper Moon. The full mechanism, with the conditions that bring out a particular power, is detailed in our article on demons’ Blood Demon Arts.

This lineage gives Muzan total powers of surveillance. He sees through his creatures’ eyes, hears what they hear, reads their thoughts from afar and can kill them by will alone. A demon who speaks his name in front of a witness dies on the spot.

Tamayo is the only one to have freed herself from this hold, thanks to her own science of blood. She then spends centuries preparing the poison that will be used against her creator.

The Twelve Moons, his personal army

Muzan organises his best demons into twelve ranks, six Upper Moons and six Lower Moons, with their number engraved in their eye. The hierarchy, the internal rules and the missions given to each are detailed in our article on the Twelve Kizuki and their ranks.

The six Upper Moons have not changed for a hundred years when the story begins. Kokushibo, Upper Moon One, is a former demon slayer. Doma, Upper Moon Two, leads a cult. Akaza, Upper Moon Three, only fights bare-handed.

The Lower Moons, on the other hand, are killed one after another by the Hashira. After Rui’s death on Mount Natagumo, Muzan summons the five survivors and executes four of them in the same scene. The details of this purge are told in our article on the Lower Moons executed by Muzan.

The only one spared, Enmu, Lower Moon One, receives an extra dose of blood and goes off to set a trap on a train. The collection of all the shop’s demons brings together the products devoted to this gallery of enemies.

This army also serves as his nervous system. Muzan summons the Upper Moons to his fortress, reads their thoughts during the meeting, and punishes on the spot anyone whose mind has displeased him. No other group in Demon Slayer works this way.

The lives he leads among humans

Muzan does not live in hiding. He settles into houses, takes a wife, raises children who are not his own, and plays the part to the end. In Asakusa, he strolls with his family in the middle of the crowd, and that is the day Tanjiro recognises him by his scent.

His last cover is the most cynical: a pale ten-year-old boy, supposedly suffering from a skin disease that keeps him out of the sun, adopted by an elderly couple who care for him devotedly. The day he hears the news about Nezuko, he kills his adoptive mother and the maid within the same minute.

The story specifies that he lived with five women during the Heian era, all of whom he drove to their deaths by the way he spoke to them alone. These successive lives are not refuges: they are sets he abandons as soon as they become inconvenient.

This family-man silhouette, pale hat on his head, exists in three dimensions among the demon figures.

Yoriichi, the only fear of his long life

Only one encounter almost brought it all to an end. In the Sengoku era, Muzan comes across a demon slayer who uses Sun Breathing and cuts him to pieces in a few seconds. He escapes by splitting into one thousand eight hundred fragments of flesh, and owes his survival to that reflex alone.

This man, Yoriichi Tsugikuni, leaves marks that centuries of regeneration cannot erase. His story and that of his twin brother are told in our article on the Tsugikuni brothers and their rift, and our page on every breathing style in Demon Slayer details the original breathing he used.

From that day on, Muzan has the wearers of hanafuda earrings hunted down, along with the family that passes on the Dance of the Fire God. The massacre of the Kamado family, in the first chapter, is not a random meal: it is the continuation of a three-century-old vendetta, whose consequences are detailed on our page about the hero of Demon Slayer and his family.

The fear born of this encounter explains a good part of Muzan’s behaviour in Demon Slayer. He delegates, he hides, he sends his Moons into contact and only appears in person once he is certain of his superiority. Three centuries later, he still refuses to speak the name of the man who cut him to pieces.

The Infinity Castle and the last night

The last act of Demon Slayer takes place in a single night.

It plays out between sunset and sunrise, a little over six hours. Muzan turns up at the Ubuyashiki estate, where Kagaya holds him back long enough to blow up the building. Tamayo appears, immobilises him and injects him with the drug that is meant to turn him back into a human.

The plan narrowly fails. Muzan neutralises the drug, but the operation costs him part of his stamina, and Shinobu’s poison speeds up his ageing: his hair turns white, his body becomes covered in mouths. Nakime then pulls everyone into the Infinity Castle and its shifting rooms, where the Hashira are scattered one by one.

The survivors hold him back until dawn. He kills dozens of lower-ranked demon slayers who throw themselves at him as shields, injects his blood into Tanjiro to destroy him from within, and loses his footing when the mark bearers resist the poison. The details of the losses can be found in our article on the Hashira who die in the story.

The sun rises and reduces him to ashes. With his last gesture, he transfers his blood and memories to the dying Tanjiro, to make him his successor. Nezuko and Kanao bring the boy back, and the reign of the first demon ends there.

This combat form is the one chosen for the largest of his figures, among all the shop’s demons.