Kokushibo

Name: Kokushibo

Human name: Michikatsu Tsugikuni

Gender: Male

Affiliation (demon): Twelve Kizuki – Upper Rank One

Former affiliation (human): Demon Slayer Corps

Height: 190 cm

Weight: 93 kg

Hobby: Go (board game)

Breathing style: Moon Breathing (Total Concentration)

Blood Demon Art: Crescent-shaped slashes

First appearance (manga): Volume 12, Chapter 98 "Upper Rank Gathering"

Anime arc debut: Demon Slayer: Kimetsu no Yaiba Swordsmith Village Arc (post-credits/upper rank meeting)

First-person pronouns: “I” / “Ore” (in Japanese original)

Twelve Kizuki number: Upper Rank One

Official popularity poll: 2nd poll – 14th place (2,938 votes)

Japanese voice actor (anime): Ryotaro Okiayu

Stage actor: Kazuki Kato

Kokushibo is the highest-ranked among Muzan Kibutsuji’s elite demons, the Twelve Kizuki, and is their oldest surviving member by the time of the main story.

He is a former Demon Slayer who, even after turning into a demon, retains full use of Total Concentration Breathing and many of his human memories and personality.

Born in the Sengoku (Warring States) period as Michikatsu Tsugikuni, he lived through the Muromachi, Azuchi–Momoyama, Edo, and Meiji eras into the Taisho period, meaning he has maintained his “strongest swordsman” status for roughly 400 years.

Like Doma, he is an ancient demon who preserves his human character and memories unusually clearly, which makes him especially dangerous and complex.

Kokushibo dresses like a traditional samurai, wearing a purple upper garment with black hakama and his long hair tied back in a single bundle.

His most striking features are his six red, gold-iris eyes arranged in three vertical pairs on his face and the flame-like markings that run from his left forehead and right neck down to his right jaw.

His two central eyes bear the characters for “Upper Rank” and “One,” marking his position in the Twelve Kizuki.

Despite originating from the Sengoku era, he has a very tall and imposing figure, standing at 190 cm, which contributes to his overwhelming presence in battle.

Kokushibo is calm, composed, and highly rational, speaking in a measured tone with frequent pauses that give his words heavy weight.

He exudes a crushing sense of pressure and dignity; even elite Demon Slayers such as Muichiro Tokito and Kaigaku describe him as terrifying beyond comparison to other Upper Ranks.

He values hierarchy and order extremely highly, a mindset rooted in his upbringing as the eldest son of a samurai house in the Warring States period.

Because that era was filled with constant upheaval and risks of assassination or rebellion, he became keenly sensitive to rank, loyalty, and the dangers of disorder.

Kokushibo is loyal to Muzan Kibutsuji and is one of the very few demons whom Muzan genuinely trusts.

He refers to Muzan respectfully as “that lord” and regards Muzan’s blood as something “that must not be spilled even a single drop,” treating him as his absolute master rather than an equal.

He is harsh toward weakness and has no qualms about cutting down frail Demon Slayers, yet he sincerely acknowledges the skill and dedication of strong opponents, especially the Hashira.

Because he views the “mark” (the Demon Slayer Crest) as a guarantee of early death before age 25, he actually laments that such hard-earned strength and technique will be lost, and thus offers such talented warriors the option of becoming demons to escape their fate and continue honing their skills.

This philosophy puts him in direct ideological conflict with Gyomei Himejima, who holds that “living and dying as a human” is a core point of pride.

Kokushibo, in contrast, abandoned his human life in pursuit of absolute strength and immortality, exchanging humanity, family, and honor for the chance to refine his swordsmanship forever.

Michikatsu Tsugikuni was born into the Tsugikuni samurai family during the Sengoku period as the older twin of Yoriichi Tsugikuni.

At that time, twins were considered ill-omened, and the younger twin, Yoriichi, who bore a strange mark on his forehead, was designated as a kind of cursed, unimportant child while Michikatsu was named the legitimate heir.

As a result, Yoriichi lived a life of extreme discrimination, while Michikatsu received all the attention and privilege of an heir.

Michikatsu initially felt pity for his brother and believed himself fortunate, but he completely misread Yoriichi’s frequent presence at their ailing mother’s side.

After Yoriichi ran away from home following their mother’s death, Michikatsu discovered her diary and learned the truth.

He realized that Yoriichi had stayed by their mother not for favoritism but to support her paralyzed left side due to illness, and that their father had planned to send Yoriichi to a temple, not knowing how extraordinary he truly was.

Upon understanding this, Michikatsu’s pity transformed into intense jealousy and hatred toward Yoriichi’s talent and goodness.

He inherited the Tsugikuni household, took a wife, and had children, attempting to live as a proper samurai, yet his heart was never free from his inferiority complex toward his brother.

Years later, he reunited with Yoriichi and witnessed his overwhelming swordsmanship and power firsthand.

Fascinated by his brother’s strength and techniques, Michikatsu abandoned his social position, his wife, and children, and joined the Demon Slayer Corps in pursuit of that same level of ability.

As a Demon Slayer, Michikatsu developed his own breathing style, Moon Breathing, as a derivative of his brother’s Sun Breathing.

He awakened the mark (the Demon Slayer Crest) and mastered the “Transparent World,” attaining a level of skill surpassing even most modern Hashira.

However, the mark came with a curse: all bearers die before the age of 25.

Realizing that his remaining lifespan was nearly gone, Michikatsu fell into despair at the thought that his hard-earned strength and sword artistry would soon disappear forever.

It was in this state that he encountered Muzan Kibutsuji.

Intrigued by breathing users and eager to recruit a marked swordsman, Muzan invited Michikatsu to become a demon, offering him virtual immortality and infinite time to refine his techniques.

Michikatsu accepted Muzan’s offer and transformed into a demon, taking the name Kokushibo.

As a sign of his betrayal, he killed the then-current Ubuyashiki clan head of the Demon Slayer Corps and presented the severed head to Muzan, completely severing his ties with the Demon Slayers.

From then on, Kokushibo served Muzan faithfully as an enforcer and assassin, tasked among other things with exterminating all Sun Breathing users and their descendants, a vendetta rooted in Muzan’s fear of Yoriichi’s power.

Over centuries, Kokushibo solidified his position as Upper Rank One, never once being dethroned in hundreds of years.

Kokushibo’s entire life is defined by his relationship with his younger twin, Yoriichi Tsugikuni.

Yoriichi was the originator of Sun Breathing and an unparalleled swordsman whose power nearly killed Muzan in a single encounter.

Even after becoming a demon, Kokushibo could never surpass Yoriichi’s talent.

Decades after his transformation, he faced his brother again.

At that time, Yoriichi was over 80 years old yet fought exactly as he had in his prime, effortlessly overwhelming Kokushibo in a duel.

Yoriichi delivered a fatal strike that would have ended Kokushibo, but died standing from old age before he could complete the killing blow.

Kokushibo survived only because Yoriichi’s life ran out mid-strike.

He was left with the bitter knowledge that even after abandoning humanity and living for centuries as a demon, he had never truly won against his brother.

Enraged and humiliated, he hacked apart Yoriichi’s lifeless corpse in a fit of fury.

However, during this frenzy, he found a small flute he had once given Yoriichi in childhood, which his brother had kept at his side for his entire life.

Realizing that Yoriichi had cherished this keepsake despite everything, Kokushibo wept.

This flute later remains hidden in his clothes even at the time of his death, symbolizing his unbreakable, twisted bond with his brother and his unfulfilled wish to be like Yoriichi.

As Upper Rank One, Kokushibo acts as a sort of disciplinarian among the Twelve Kizuki.

He is not loud or temperamental, but his quiet, oppressive presence and sudden, precise punitive attacks maintain order.

He strictly enforces the hierarchy of the Upper Ranks.

When Akaza strikes Doma during the Upper Rank meeting, Kokushibo silently cuts off Akaza’s left arm so quickly that Akaza does not notice at first.

He admonishes Akaza, telling him that if he dislikes Doma, he should formally invoke a rank-challenge duel rather than disrupt the order with an unsanctioned attack.

To Doma, who laughs it off, Kokushibo explains that he is not doing this for Doma’s sake but out of concern that cracks in the hierarchy and subordination system could weaken their entire group.

Kokushibo respects Akaza as a fellow martial artist who rose to Upper Rank Three purely through combat prowess.

When Akaza once challenged him in an official rank duel, Kokushibo won decisively but chose not to devour him, allowing him to live because he appreciated his warrior spirit.

Akaza later declares, “I will definitely kill you,” to which Kokushibo simply replies, “Then strive for that.”

During the Infinity Castle battle, when Kokushibo learns that Akaza has been defeated, he is uncharacteristically enraged and disappointed, calling Akaza “feeble” and lamenting that he failed to fulfill his promise to surpass him.

Kokushibo also spares Kaigaku Inadama, a former Demon Slayer who begs for his life.

Instead of killing him, Kokushibo gives Kaigaku Muzan’s blood, turning him into a demon and later recommending him as the new Upper Rank Six, which demonstrates Kokushibo’s willingness to cultivate promising or compatible fighters.

According to the official fanbooks, Muzan regards Kokushibo as a “business partner.”

Muzan values him not only for his immense strength but also for his cautious, analytical approach to battle.

Kokushibo’s loyalty is genuine, and he never entertains thoughts of betraying Muzan.

He states that Muzan’s presence actually makes life easier for him because he does not need to conceal his emotions or motivations.

After recruiting Michikatsu as Kokushibo, Muzan soon suffered his near-fatal defeat at the hands of Yoriichi.

In the aftermath, Muzan hid himself from the public eye and tasked Kokushibo with exterminating all Sun Breathing users and their descendants, hoping to erase the threat that Yoriichi’s legacy posed.

Kokushibo’s overall combat power is second only to Muzan Kibutsuji himself.

He combines the physical advantages of an Upper Rank demon with the refined swordsmanship of a top-tier Demon Slayer and several rare abilities.

He possesses the standard high-speed regeneration of a powerful demon, healing grievous injuries such as a destroyed shoulder almost instantly.

However, he does not rely on regeneration alone and prefers to avoid or parry attacks through superior skill and awareness.

His centuries of battle experience give him exceptional insight, tactical judgment, and the ability to quickly analyze unfamiliar techniques.

He can calmly respond to surprise attacks or new abilities almost as soon as he sees them.

Kokushibo also benefits from the mark (Demon Slayer Crest), which greatly enhances his physical capabilities.

Unlike human users who pay with their lifespan, Kokushibo as a demon suffers no such drawback and can maintain his marked state indefinitely.

On top of this, he has mastered the Transparent World, allowing him to read opponents’ movements by observing their muscles, bones, and breathing.

These senses, combined with his Blood Demon Art and Moon Breathing, make him nearly untouchable even when facing multiple Hashira at once.

Moon Breathing is Kokushibo’s original sword style, developed when he was still human as a derivative of Yoriichi’s Sun Breathing.

After becoming a demon, he fused this style with his Blood Demon Art, creating techniques that use both physical sword swings and supernatural crescent slashes.

Moon Breathing possesses at least sixteen named forms, more than any other breathing style revealed in the series.

This large repertoire lets Kokushibo adapt instantly to changing situations, making it extremely difficult for opponents to find openings.

Each form features abnormal speed and wide attack ranges, often capable of striking multiple enemies in a single swing.

The crescent-shaped slashes generated by his sword make his attacks multi-layered and hard to dodge even if the blade itself is avoided.

Muichiro Tokito describes Kokushibo’s speed as “otherworldly,” while Sanemi Shinazugawa calls it “too fast, it’s insane,” and Gyomei Himejima notes that the speed alone is dangerous.

Because of this, simply surviving a brief exchange with Kokushibo is already a major feat.

Forms One through Six are used with his standard sword size.

These techniques still carry traces of the swordsmanship he had as a human, but many now incorporate ranged crescent slashes and multiple simultaneous attacks, reflecting his Blood Demon Art.

Forms Seven through Sixteen are used when he transforms his blade into a massive, branched greatsword.

These latter forms greatly magnify his attack radius and destructive power, functioning as upgraded versions of the earlier techniques and turning the battlefield into a lethal storm of steel and crescents.

Kokushibo’s Blood Demon Art manifests as crescent-shaped slashing blades that appear along or beyond the path of his sword swings.

These crescents can be chained together into large, swirling slash storms or fired independently as flying blades.

The crescents unpredictably vary in size, angle, and trajectory, constantly changing in shape and coverage.

Even if an opponent manages to avoid the physical blade, the irregular crescents often catch them from unexpected angles, slicing flesh and limbs with ease.

This Blood Demon Art is seamlessly integrated into his Moon Breathing forms.

His swordsmanship and Blood Demon Art are so thoroughly combined that distinguishing between “sword” and “ability” in his attacks becomes nearly impossible.

In extreme situations, Kokushibo can sprout blades from all over his body.

When he does so, countless crescent slashes erupt from his entire form at once, creating a horrifying counterattack that can slice through multiple adversaries simultaneously.

Kokushibo wields a unique sword known as “Kyokoku Kamusari,” a living blade created from his own blood, flesh, and bone.

At first glance it resembles a normal Japanese katana, but its blade and guard are veined like living tissue and studded with numerous eyes.

These eyes are the sources of his crescent-shaped slashes, and they seem to perceive the battlefield along with Kokushibo.

The sword’s fittings resemble the weapon he used as a human, including a similar four-lobed guard and black wrapping on the hilt.

Because the blade is made from his own body, it shares his demonic regenerative capabilities and can change shape at will.

It can grow, split, or completely reset its form after being damaged, allowing Kokushibo to fight without worrying about his weapon breaking.

One major drawback is that, since it is made of demonic flesh, it burns and disintegrates when clashing with high-purity crimson ore steel, the material used for Nichirin blades.

In practice, however, Kokushibo’s overwhelming power usually prevents such direct, prolonged blade-locks from mattering.

When Kokushibo respects an opponent’s strength, he transforms Kyokoku Kamusari into a monstrous greatsword with three branching points, far longer and thicker than a normal blade.

In this form, the number and density of crescent slashes increase dramatically, turning combat into a true nightmare of unavoidable attacks.

The mark is a special ability that appears on the bodies of elite Demon Slayers after reaching extraordinary physical and breathing states.

When activated, it dramatically boosts physical abilities, perception, and fighting power.

The price for humans is severe: all marked individuals die before the age of 25, a limit that Michikatsu discovered to his despair.

This looming death is part of what pushed him toward accepting Muzan’s offer and becoming a demon.

As a demon, Kokushibo bears the mark permanently and without side effects.

The flame-like markings on his forehead, neck, and cheek are a visible remnant of this crest, helping to fuel his terrifying combat performance.

The Transparent World is a heightened perception state achieved by only a handful of swordsmen.

In this state, a user sees through an opponent’s skin to their muscles, bones, blood flow, and breathing, allowing them to predict movements and attack with incredible precision.

Kokushibo, like his brother Yoriichi, mastered this ability while still human.

He can read his enemies’ micro-movements and preempt their strikes, making his defense and offense almost impossibly efficient.

The Transparent World also allows a user to suppress their own killing intent, making their movements harder to anticipate.

Whether Kokushibo consistently hides his killing intent is not fully clear, but his use of the Transparent World is central to his fighting style.

Within the Twelve Kizuki, Kokushibo has maintained his rank as Upper Rank One for hundreds of years.

In an organization plagued by constant internal conflicts and rank challenges, his unbroken dominance marks him as truly exceptional.

Former Demon Slayers and demons alike speak of him with awe and dread.

Kaigaku recalls him as a terror so overwhelming that “every cell in his body screamed in fear,” while Muichiro Tokito, who had already defeated an Upper Rank by himself, finds Kokushibo’s aura and menace incomparable.

Kokushibo has personally executed countless Demon Slayers across multiple eras.

He is said to have fought and judged several generations of Hashira, watching techniques evolve yet always staying ahead of them in sheer strength and mastery.

His approach to combat is methodical rather than sadistic.

He analyzes opponents calmly, praises those with strong resolve and technique, and occasionally offers the strongest the chance to survive as demons, believing that their extinction as short-lived humans is wasteful.

Kokushibo’s first on-page appearance occurs during the Upper Rank gathering in the Infinity Castle after the defeat of Gyutaro and Daki.

The loss of Upper Rank Six breaks a 113-year streak of uninterrupted Upper Rank victories, prompting Muzan to summon all surviving Upper Ranks.

When Muzan angrily criticizes the demons for failing to locate the Ubuyashiki mansion, Kokushibo answers honestly that they have no excuse, acknowledging that the Ubuyashiki family hides themselves extremely well.

His calm, straightforward response contrasts with the nervous or sycophantic behavior of other demons, showing why Muzan values him.

When Akaza strikes Doma’s head in frustration at being mocked, Kokushibo silently cuts off Akaza’s arm to enforce discipline.

He explains that disputes should be settled through formal rank-challenge duels, not chaotic brawls that undermine their hierarchy.

After this, he quietly encourages Akaza’s declaration that he will one day kill Kokushibo.

Then he leaves without making a sound, heightening the sense of his eerie, dignified presence.

During the final battle in the Infinity Castle, Kokushibo is transported to a separate area where he soon encounters Muichiro Tokito.

Muichiro immediately senses that Kokushibo is on a completely different level compared to the Upper Rank he had previously defeated.

Kokushibo tells Muichiro that his human name is Michikatsu Tsugikuni and reveals that Muichiro is descended from the child he left behind in the Tsugikuni clan.

This means Muichiro is Kokushibo’s distant descendant on his father’s side.

Muichiro is shaken by this revelation but quickly regains composure and attacks Kokushibo, who easily evades and praises Muichiro’s skill and resolve.

When Muichiro activates his mark and uses Mist Breathing Seventh Form: Obscuring Clouds, Kokushibo analyzes and sees through the technique almost instantly.

He draws his blade and cuts off Muichiro’s left arm in a flash.

Despite this, he evaluates Muichiro as valuable and stakes him to a pillar with Muichiro’s own Nichirin blade, intending to keep him alive and later have him turned into a demon accepted by Muzan.

Kokushibo carefully stops the bleeding from Muichiro’s severed arm to prevent him from dying prematurely.

This act shows that Kokushibo genuinely wanted to preserve Muichiro as a potential demon ally, not merely toy with him.

Soon after, Genya Shinazugawa appears and attempts a surprise attack with demon-fusing bullets from hiding.

Kokushibo senses him, dodges effortlessly, and in a single series of movements cuts off Genya’s left arm, then his right arm, then bisects his torso, and finally severs his neck.

Just as Kokushibo moves to finish Genya completely, Sanemi Shinazugawa arrives and intercep