Kokushibo is the Upper Rank One of the Twelve Kizuki, making him the most powerful demon under Muzan Kibutsuji. Before becoming a demon, he was known as Michikatsu Tsugikuni, a former Demon Slayer and the twin brother of the legendary swordsman Yoriichi Tsugikuni, the creator of the Sun Breathing style. Driven by envy and fear of death, Michikatsu abandoned his humanity and became the very thing he once hunted — a demon.
Kokushibo serves as one of the final antagonists of the series, embodying themes of jealousy, legacy, and the tragedy of lost humanity.
Appearance[]
As a Demon:
Kokushibo has a tall, imposing figure with long, flowing black hair that fades into red tips. His most distinctive feature is his six eyes, arranged in a symmetrical pattern across his face, all of which have the kanji for "Upper One" (壱) inscribed in them. He wears an elaborate, dark-colored kimono with a rippling pattern and wields a katana formed from his own flesh and blood.
His demonic presence is regal and terrifying, exuding power and authority. Despite his monstrous form, he retains a calm and dignified air that reflects his samurai background.
As a Human (Michikatsu Tsugikuni):
In his human years, Michikatsu had a handsome and composed appearance, resembling a more somber version of his brother Yoriichi. He dressed in traditional Demon Slayer Corps attire and carried himself with the pride of a noble warrior. His jealousy and inner torment were carefully hidden beneath a stoic exterior.
Personality[]
Kokushibo is calm, stoic, and articulate. He maintains a sense of formality and honor, even in combat, speaking with measured respect to powerful opponents. However, beneath this facade lies a man consumed by envy, fear of death, and self-loathing.
His primary internal conflict is his lifelong resentment toward Yoriichi, his younger twin brother, whose genius with the sword and innate talent eclipsed Michikatsu in every way. Even after becoming a demon and gaining immense power, Kokushibo could never let go of his inferiority complex.
Despite rejecting his humanity, Kokushibo still follows a warrior's code and often shows disdain for demons who behave like beasts. However, he also represents the danger of clinging to ambition and pride at the cost of one's soul.
Story[]
Backstory[]
Born as Michikatsu Tsugikuni, he was the elder twin of Yoriichi, a boy born with the Demon Slayer Mark and immense natural talent. Their father feared Yoriichi’s mark and planned to kill him, but their mother protected Yoriichi until she passed away. Michikatsu grew up in Yoriichi’s shadow, constantly feeling inferior.
Even after becoming a skilled swordsman and joining the Demon Slayer Corps, Michikatsu was never able to match Yoriichi’s greatness. This unrelenting jealousy, coupled with his growing fear of aging and death, led him to accept Muzan’s offer and become a demon — taking the name Kokushibo.
Over the centuries, Kokushibo remained loyal to Muzan, ascending to the highest rank among the Twelve Kizuki. However, he never forgot his brother or the pain of being second-best.
Infinity Castle Arc[]
During the final confrontation between the Demon Slayer Corps and Muzan’s forces, Kokushibo faces off against three of the strongest swordsmen:
- Muichiro Tokito, the Mist Hashira and descendant of Kokushibo.
- Genya Shinazugawa, a Demon Slayer with the ability to temporarily become part demon.
- Sanemi Shinazugawa, the Wind Hashira.
- Gyomei Himejima, the Stone Hashira and the strongest Hashira of the current era.
The battle is intense and long. Kokushibo showcases overwhelming strength, effortlessly countering their combined assault. He kills Muichiro and severely wounds Genya, but the persistence and cooperation of the remaining Hashira begin to turn the tide.
In a climactic moment, Sanemi and Gyomei manage to decapitate Kokushibo, but his body begins to regenerate due to his immense willpower and connection to Muzan. However, he is finally defeated when he catches a glimpse of himself and realizes what he has become — a twisted, monstrous form, far removed from the samurai he once was.
In his final moments, Kokushibo reflects on his life and is overwhelmed by regret, longing for the simplicity and purity of being human. His death is solemn — a tragic end to a man who could never let go of his pride.
Powers and Abilities[]
1. Moon Breathing (月の呼吸, Tsuki no Kokyū)[]
As a former Demon Slayer and swordsman, Kokushibo uses his original breathing style — Moon Breathing, a derivative of the Sun Breathing style. His mastery of this style as a demon is terrifyingly powerful.
His Moon Breathing techniques combine bladed slashes with chaotic, crescent-shaped shockwaves that vary in size and speed. These erratic, beautiful attacks are extremely difficult to predict or block.
Some of his known techniques include:
- First Form: Dark Moon, Evening Palace – Unleashes crescent-shaped blades in an erratic spiral.
- Sixth Form: Perpetual Night, Lonely Moon - Incessant – A barrage of continuous crescent slashes that overwhelm the opponent.
- Sixteenth Form: Moonbow – Half Moon – An incredibly fast and precise strike that cuts down multiple enemies.
2. Flesh Katana[]
Kokushibo’s weapon is a katana formed from his own flesh and blood, embedded with eyes and capable of changing its size and shape. It enhances his Moon Breathing and regenerates if damaged. This organic blade symbolizes his complete transformation and loss of humanity.
3. Demon Physiology[]
As the Upper Rank One, Kokushibo has immense regenerative abilities, superhuman strength, incredible speed, and enhanced perception. His multiple eyes give him heightened awareness of his surroundings and allow him to see through the breathing techniques of opponents.
4. Swordsmanship Mastery[]
Even before becoming a demon, Kokushibo was one of the finest swordsmen of his era, second only to Yoriichi. After centuries of refining his skills and enhanced by demonic power, his swordsmanship became nearly invincible, capable of slashing through buildings, weapons, and other high-ranking fighters with ease.
5. Demon Slayer Mark[]
As a human, Michikatsu awakened the Demon Slayer Mark, which temporarily increased his physical capabilities. However, he was unwilling to die young as the mark users were fated to, and this fear drove him to become a demon.