Moon Breathing: Kokushibo’s sixteen forms

He has six eyes, a sword made of his own flesh, and four hundred years of training behind him. Kokushibo is the only demon in Demon Slayer to wield a breathing style, like the demon slayers he fights. Moon Breathing is the legacy of a man who sacrificed everything to catch up with his brother, and never managed it.

Here is where this breathing style comes from, its known forms, the weapon that carries it, and the story of the twin who created it. To place Moon among the other breathing styles, our page on all the Demon Slayer breathing styles presents the fourteen known styles.

This article reveals elements of the Infinity Castle arc that the anime has not yet adapted.

What is Moon Breathing?

In Demon Slayer, Moon Breathing, Tsuki no Kokyū in Japanese, is a style derived from Sun Breathing, like the five basic styles. But it is not one of them. Michikatsu Tsugikuni created it alone, unable to master his brother’s Sun, and he kept perfecting it after becoming a demon.

Its principle is unique: each cut comes with a volley of small crescent-moon blades, of different sizes and speeds, which whirl around the main blow. The opponent must dodge not only the blade, but also all these unpredictable shards, which change shape from one second to the next and strike well beyond the sword’s reach. Even a Hashira struggles to read such an attack.

It is also the only breathing style practised by a demon. Kokushibo’s regeneration, his resilience and his Upper Moon strength add to a swordsman’s technique brought to its peak. Our article on the breathing tree shows where Moon sits in the whole family.

The forms of Moon Breathing

Moon Breathing has sixteen forms. Eleven have a known name, all shown in Muzan’s castle. The table sets them out in order, with the Japanese name and its translation.

The names are of rare elegance, like the cultivated man Michikatsu was. They evoke night palaces, mirrors, dragons and moonbows. Depending on the translation, our portrait of Kokushibo sometimes words them differently, but the image stays the same: a cold, beautiful and deadly moon.

The last forms are the most terrible. Kokushibo unleashes them when his sword lengthens and splits into several branches, each covered in eyes. At this stage, his cuts cover dozens of metres, and the Hashira can only dodge them by running.

Our 26 cm figure makes this red crescent spin behind Kokushibo, sword in both hands, above a base of broken roof tiles. It is filed in the complete Kokushibo collection and the demon figures collection.

A sword of flesh covered in eyes

Kokushibo’s sword is not forged: it was born from his body. Having become a demon, Michikatsu grew a blade from his own flesh, covered in eyes that look in every direction. He reforms it at will, even broken, in barely a few moments. It even has a name, Kyokokukamusari.

Over the course of the fight, this blade lengthens and branches out, until it looks like a tree of flesh bristling with branches. It is this sword that lets Moon’s last forms reach such a range. No human weapon could do as much.

This yellow-eyed blade comes as a replica, accompanied by three crescent blades, a purple guard and a pink sheath scattered with white flowers. It is filed in the katanas collection and among the demon products.

What Moon demands of the fighter

In Demon Slayer, Moon Breathing has only ever been practised by one man, and for good reason. It demands the mastery of an outstanding swordsman, trained in the age of the great warriors of the Sengoku era, and perfect breathing, maintained permanently. Michikatsu already had these qualities before becoming a demon.

The crescent moons, for their part, demand more. They stem partly from Kokushibo’s demon nature, from his ability to make blades spring from his body and his sword of flesh. A human demon slayer probably could not reproduce this effect. Moon is a style halfway between the demon slayers’ technique and a demon’s Blood Demon Art.

Finally, it demands time, a great deal of time. Kokushibo enriched it for more than four hundred years, adding form after form, up to sixteen. It is the fruit of an obsession, that of surpassing a brother dead for centuries. Our page on the Demon Slayer Hashira presents those who had to face it.

Michikatsu and Yoriichi, the Tsugikuni twins

In Demon Slayer, Michikatsu and Yoriichi Tsugikuni are born twins in the Sengoku era, into a samurai family. Yoriichi bears a mark on his forehead from birth, which their father takes for a bad omen. Michikatsu, the elder, is destined to inherit. Yet he discovers that his little brother, whom he thought weak, has a talent for the sword that surpasses anything he will ever reach.

Later, the two brothers meet again in the Demon Slayer Corps. There Yoriichi creates Sun Breathing, which no one manages to learn, and from it all the other breathing styles are born. Michikatsu tries, fails, and invents the Moon instead. He also awakens the Demon Slayer Mark, which multiplies strength but condemns its bearer to die before the age of twenty-five.

That is where Muzan steps in. He offers Michikatsu what he lacks: time. To live forever, and so to have eternity to catch up with his brother. Michikatsu accepts. To join Muzan, he betrays the Demon Slayer Corps, kills the head of the Ubuyashiki family of the time and brings his head to the first demon. The brother of the greatest demon slayer in history thus becomes Muzan’s most powerful servant, and will remain so for centuries. Our article on Kokushibo and Yoriichi tells their story, and the one on Yoriichi Tsugikuni, the greatest swordsman presents the brother he never matched.

The two brothers face each other on our 29 cm light-up figure, offered in two models: Kokushibo emerging from a purple arc, or Yoriichi surrounded by a wave of flames. It is filed in the complete Yoriichi Tsugikuni collection.

The two brothers’ last encounter

Decades pass. Michikatsu has become Kokushibo, Upper Moon One. One evening, he meets Yoriichi again, whom he thought long dead like all bearers of the mark. His brother is over eighty, and he weeps on seeing what Michikatsu has become.

Yoriichi draws. Kokushibo knows from the first movement that he is going to lose: even old, his brother remains undefeated. But as he is about to strike, Yoriichi dies of old age, standing, without completing his blow. Kokushibo, mad with rage, slices through his brother’s body. In his clothes, he finds the little flute he had made for him when they were children.

Kokushibo will keep this flute for centuries. It says everything about what gnaws at him: a hatred mixed with a love he refuses to admit to himself. In Demon Slayer, no demon is as tragic. Our page on the demons and the Twelve Kizuki presents Kokushibo among the Moons.

Muichiro, the unexpected heir

Before becoming a demon, Michikatsu had children. His bloodline crossed the centuries down to the Tokito twins, Muichiro and Yuichiro. Muichiro, the Mist Hashira, is therefore Kokushibo’s distant descendant.

In Muzan’s castle, Kokushibo recognises his own blood in him. He judges him worthy and offers him, as Muzan had done for him, to become a demon. Muichiro flatly refuses, and fights to the very end. Our article on Mist Breathing tells of this fight from Muichiro’s point of view.

This encounter gives the fight a family dimension. The demon who betrayed his own for eternity faces a child of his blood who prefers to die human. It is one of the cruellest mirrors in the whole series. Michikatsu had chosen eternity so as not to die at twenty-five; his descendant, at fourteen, chooses to die rather than resemble him.

The fight in the castle

In Demon Slayer’s castle, Kokushibo faces four demon slayers: Muichiro Tokito, Gyomei Himejima, the Stone Hashira, Sanemi Shinazugawa, the Wind Hashira, and Genya, Sanemi’s brother. It is the hardest fight in the whole castle. Moon Breathing shows all its power there, and the Hashira all awaken the mark to stand up to him.

Muichiro and Genya lose their lives, but their sacrifice lets Gyomei and Sanemi cut through the demon’s neck. Kokushibo then tries to regenerate, and catches sight of his reflection in a blade: a monster covered in eyes, with nothing human left. He wonders whether this is what he wanted to become. His body stops reforming, and he disappears, leaving only Yoriichi’s flute.

Our article on Stone Breathing and the one on Wind Breathing tell of this fight from the Hashira’s side. To find out where to read this scene, our article on the chapter to read after the anime tells you where to pick up.

Moon on screen

Viewers of the Demon Slayer anime glimpsed Kokushibo at the meeting of the Upper Moons, at the start of season 3, in Muzan’s castle. His silence, his six eyes and his samurai attire were enough to establish his menace. His forms, however, have not yet been shown on screen.

His big fight belongs to the rest of Infinity Castle, expected after the first film released in 2025. Fans are waiting to see how the studio ufotable will render these crescents whirling by the dozen around each cut. Our article on the Infinity Castle sequel takes stock of what we know, and our page Demon Slayer in what order, seasons and films places each film in the story.