The ugliness of having my head cut off, my body diced and crushed into pieces, and being unwilling to accept defeat. A disgrace to life. Have I lived hundred of years for this?... Was I so afraid of defeat that I became a monster?... Did I want to be strong even if it meant eating people?... Did I become this miserable creature because I didn't want to die?... No. I... I just... Yoriichi. I just wanted to be like you...
— Kokushibo in Samurai
Over four centuries ago during the Sengoku Era, Kokushibo was a human by the name of Michikatsu Tsugikuni (
Kokushibo is a pale-skinned, tall man with long and spiky, black hair that he kept in a ponytail. He has three sets of eyes on his face with red sclera and yellow irises. His middle set of eyes featured the kanji of Upper Rank (
Kokushibo wore a purple-and-black-patterned kimono and black hakama pants tied with a white cloth. He carried a sword at his waist that had eyes in the space between the tsuka wrapping of the handle of his sword. The guard and blade were also later revealed to have eyes and veins.
As a human, Kokushibo's appearance was nearly identical to his Demon form, with the exception of the number of eyes, his prominent eyebrows, and notably less pale skin. His eyes had brown irises and normal, white sclera as a human.
After being beheaded by Sanemi Shinazugawa and Gyomei Himejima, Kokushibo evolved into a grotesque version of his Demon appearance, with protruding fangs, a pair of horns, and several sharp appendages from his body.
Kokushibo was often a reserved Demon, and with such little knowledge about the Upper Ranks, not much was originally known about him. He was an adamant rule-follower, punctual, and he showed a great deal of respect to the hierarchy of the Twelve Kizuki - as seen at the Upper Ranks Gathering. Kokushibo was portrayed to be humble as well, and he did not hesitate to admit his failure or complain of any difficulty. He displayed a strong sense of loyalty towards Muzan Kibutsuji, with most of his actions being done with the sole purpose of fulfilling Muzan's goals.
Despite exhibiting outward reservation and humility, he was also rather cold; his words could be extremely harsh, especially when reprimanding individuals. His threats came off as nothing short of cruel and overwhelmingly serious, and he demanded absolute obedience.
He had a complex relationship with his human past. He showed something of warmth towards his descendant Muichiro Tokito, commending his skills and resolve, and moved to convert Muichiro into a Demon to spare his life. At the same time, he referred to Muichiro and his abilities as the natural result of his "cells" being passed down.
It was revealed that as a human, Kokushibo harbored an immense sense of envy towards his younger twin brother, Yoriichi Tsugikuni, for his natural talent and incredible abilities. These feelings of jealousy and contempt strengthened upon seeing his brother aged to an old man despite Yoriichi awakening his Demon Slayer Mark, which was to supposedly doom him to die at the age of 25. However, despite this immense jealousy, spite, and outright hatred he harbored for Yoriichi, he still deeply cared for and loved his brother, as seen when he was touched by Yoriichi treasuring the handmade flute he had made for him as children. Kokushibo shed genuine tears over his brother's death, and even went as far as keeping the flute itself for the following centuries as a memento to his beloved and hated younger brother.
In his duel against Gyomei Himejima, the Demon's banter suggested a fear of death. When Gyomei's marks appeared, Kokushibo preemptively bemoaned the loss of a talented fighter and urged him to become a Demon to continue honing his skills. He seemed surprised when Gyomei vehemently rejected his offer and called his mentality pathetic.
Likely a result of his inferiority complex and his immense desire for strength, Kokushibo feared the prospect of suffering defeat. So much so, he became increasingly more aggressive and agitated when being pushed further into a corner, causing him to become more desperate in his attacks and the use of his Demon power. During his battle with the Hashira, he came to realize the steep price he had paid for the strength he so much desired, becoming an ugly monster far away from his idealized dream of a strong samurai just like his brother, symbolizing how much his deep ambitions and resentment had warped him for the worst. Later upon his death, he greatly lamented and regretted his choices in his life and began to openly question himself if the path he walked was truly the right one. With that being said, Kokushibo accepts his death and decides to stop regenerating while blaming himself and his existence.
Abilities and Powers
Overall Abilities: Kokushibo was an extraordinary and powerful swordsman, proven to be the strongest of the Twelve Kizuki and the second strongest Demon in the series, just behind Muzan Kibutsuji. As one of the oldest Demons in the series, he had battled numerous Demon Slayers and obtained vast experience and knowledge of combat. He was able to easily decipher the techniques and skills of at least two Hashira and overwhelm them in battle. As a Breath Style user, he possessed tremendous levels of strength and reflexes that were further enhanced by his Demon physiology.
These overall abilities and skills allowed Kokushibo to defeat two Hashira with minimal effort and then fight against both Sanemi and Gyomei, the latter of which was considered to be the most powerful Demon Slayer in the Demon Slayer Corps. Even when Gyomei and Sanemi awakened their Demon Slayer Marks, which increased one's physical abilities way above their normal limit, he was still capable of holding his own against the both of them simultaneously.
When he started using his more of his power, Kokushibo managed to overwhelm both Gyomei and Sanemi, both of whom were boosted by their Demon Slayer Marks. As a testament to his might, it ultimately took a combo of attacks from Gyomei, Sanemi, Muichiro and Genya to even land a significant injury on him. In the end, Kokushibo's loss was mostly a result of his sudden choice to stop regenerating and began crumbling due to realizing his mistake, rather than the skills of his opponents.
- Immense Strength: Kokushibo has displayed incredible physical strength, lifting a gigantic sword that is three times heavier than a regular katana and swinging it incessantly at subsonic speeds without rest or effort. Since he assimilated more of Muzan Kibutsuji's blood than Upper Rank 3, Akaza, it can be safely assumed that Kokushibo possessed greater physical strength than him.
- Immense Speed & Reflexes: Kokushibo possessed immense levels of speed, as shown when he outpaced Muichiro's Breathing Techniques with great ease. Muichiro himself stated that Kokushibo's speed was in another dimension compared to the Hashira. Sometimes he could unleash bursts of speeds or sword slashes that evade the senses of both Sanemi Shinazugawa and Gyomei Himejima. He could also move so fast that it made him seem like he teleported.
- Limitless Stamina & Endurance: Kokushibo possesses absolute and infinite stamina and vitality, never tiring and always remaining in optimal physical and mental condition all the time as well as being able to endure waves of onslaught as if it were nothing. Despite having his ear, then limbs and whole chunks of his body being repeatedly torn off and destroyed, he never once showed a sign of pain or agony. Even when his head was being crushed by Gyomei Himejima's spiked flail, he remained resilient.
- Immense Durability: Kokushibo had displayed immense physical durability as seen when despite Gyomei using both his flail and axe to attack both ends of his neck, it still didn't budge. His neck was only severed thanks to both the combined efforts of both Gyomei and Sanemi putting all of their strength into forcing his neck to be sliced with Gyomei's axe, along with both of their weapons turning crimson red.
- Tactical Intellect: As a talented swordsman who has existed for over four centuries, Kokushibo has experienced countless battle situations and threats which he has learnt to overcome and circumvent. This was displayed during his battle with three Hashira and Genya Shinazugawa, where he was able to adapt to their special and unique fighting styles and tactics nigh instantaneously after witnessing it. For example, after Muichiro Tokito unleashed his first attack against the Upper Rank, he was able to determine he was a user of Mist Breathing, a talented one at that. This was further accentuated through Kokushibo being able to take on Sanemi Shinazugawa and Gyomei Himejima simultaneously despite both of them being marked and being users of different Breathing Styles, meaning he’d have to deal wit 2 vastly different opponents at once. Which he did so successfully, even overwhelming them multiple times.
- Swift Intellect: As one of the fastest beings in existence, Kokushibo had a mind that is able to process information and think at similar speeds. This was mainly displayed during his battle with 4 Demon Slayers when he was able to judge and accurately discern their movements and techniques even while moving at above subsonic speeds.
- Immense Regeneration: Kokushibo possessed incredible regeneration, able to regenerate his ear and right arm after getting cut by Gyomei with no effort. Later, upon being decapitated by two Hashira, Kokushibo was able to regenerate his entire head and successfully conquered death by beheading, a feat only accomplished by two other Demons: Akaza and Muzan. However, the process was slower than with Muzan and more unstable than Akaza, causing him to take on a monstrous form.
- Demon Slayer Mark: A special Mark worn by certain "awakened" Demon Slayers that resembles Demon Marks. Its specific abilities are unknown, but what is know is that it drastically improves the abilities of the Demon Slayer, making them much stronger, faster and able to react quicker than what they can achieve normally, though at the cost of being cursed to die at the age of 25. As a Demon, not only was Kokushibo no longer bound by the curse, but the Mark's abilities were enhanced even further than when he was a human.
- Transparent World (
透き 通る 世 界Sukitōru Sekai?): Similar to Tanjiro, Kokushibo has obtained the ability to see the "Transparent World" through the use of his three pairs of eyes. This grants him superhuman kinetic vision similar to Kanao Tsuyuri, allowing him to see the muscles, blood flow, and joint movement of his opponents. He can accurately predict and anticipate the movements and attacks of his opponents with this ability. He was also able to identify that Muichiro was his descendant, immediately discern the skill level of Muichiro, Sanemi, and Gyomei with one look, and see that Genya Shinazugawa consumed Demons to gain strength by looking into his cellular structures.
- Transparent World (
- Flesh Manipulation: Like all Demons, Kokushibo possesses the ability to manipulate his flesh. He used this ability to grant himself multiple eyes that augment his vision to supernatural levels. He has also used this ability to create an extremely durable and sharp katana, complete with a handguard and scabbard. Because of this, his katana can never be destroyed as he can regenerate it like he would with normal wounds.
- Sword Manipulation: Kokushibo reveals that he had detached some of his own flesh and shaped it into the katana that he uses in battle. The blade possessed numerous eyes in the blade, handle, and guard, allowing him to have an increased range of vision while using it in battle. Since the blade was also created from his flesh, it could easily regenerate if destroyed or chipped. This ability is shown when the blade returns to its original shape in his battle with Gyomei. Kokushibo also displayed the ability to freely manipulate the form of the blade, growing three additional blades from the original blade to increase its reach and further increase its size. While engaging in combat, he can manipulate the length and size of his sword strikes, allowing him to cover a distance normally unachievable by a human swordsman. Later, Kokushibo also displayed the ability to grow and protrude multiple blades from his own body, allowing him to perform a multitude of slashes from them without a swinging motion. This attack was powerful enough to easily blow away two Hashira and destroy Genya's Blood Demon Art, as well as slice in half numerous columns in the room, from just its activation; the full usage of the Blood Demon Art being unknown.
- Demonic Transformation: Later, upon regrowing his head while battling Gyomei and Sanemi, Kokushibo was able to transform himself into a demonic, monstrous form with several appendages on his back that enhanced all of his abilities and powers to presumably the same level as the Demon King, Muzan Kibutsuji.
- Crescent Moon Blades: Complementing his combat style: the Moon Breathing, his Blood Demon Art allows him to create dozens of sharp blades shaped like a crescent moon with every sword slash that constantly change in size, length and speed. The crescent blades have been shown to be either bright yellow or bright blue in color. This enhances the lethality of his techniques, allowing him to overwhelm a marked Hashira, Muichiro Tokito and keep up with two other stronger marked Hashira, Sanemi Shinazugawa and Gyomei Himejima.
- Indomitable Will: Solely because of his goal to surpass his younger twin brother, Yoriichi Tsugikuni, Kokushibo possesses an indomitable and undaunted will and spirit. When he was about to get killed, he forced his regeneration to evolve, and regrew his own head with a myriad of enhancements, all because he didn't allow himself to die until he accomplished his goal.
- Master Swordsman: Due to training and refining his swordsmanship skill for over 400 years and getting a major boost to his physical capabilities, Kokushibo has become the most powerful and skilled swordsman in the modern era, and the second strongest swordsman in existence, behind his younger twin brother, Yoriichi Tsugikuni. With his phenomenal skill in wielding a katana, he could singlehandedly take on the two strongest Hashira in the Demon Slayer Corps when they were marked as well as a marked child prodigy Hashira and a Demon Slayer gifted with the ability to gain demonic abilities
- Enhanced Breathing Techniques: As a Demon, Kokushibo's Breathing Techniques has been enhanced to heights beyond even what Hashira can achieve. His former position along with swordsmanship abilites was analogous, more than likely surpassing to that of a Hashira prior to becoming a Demon, as well as his Demon Slayer Mark and being an Upper Rank, showing that his skill and efficiency with Total Concentration Breathing (
全 集 中の 呼 吸Zen Shūchū no Kokyū?) is almost unparalleled, with only his naturally-gifted brother surpassing him.
Moon Breathing (
- First Form: Dark Moon - Evening Palace (
壱ノ 型 闇 月・ 宵の 宮Ichi no kata: Yamidzuki - Yoi no Miya?) - Kokushibo draws his sword and slashes swiftly in a single motion; like with all Moon Breathing techniques, numerous chaotic crescent blades originate from the slash. This technique is reminiscent of Iaijutsu.
- Second Form: Pearl Flowers Moongazing (
弐の 型 珠 華ノ 弄 月Ni no kata: Shuka no Rōgetsu?) - Kokushibo performs several slashes that defend him from incoming attacks while also creating a barrage of crescent blades.
- Third Form: Loathsome Moon - Chains (
参ノ 型 厭 忌 月・ 銷り San no kata: Enkidzuki - Tsugari?) - Kokushibo swings his sword rapidly in two gigantic crescent slashes, from which a storm of smaller crescents spread. This technique causes huge destruction in a small area.
- Fifth Form: Moon Spirit Calamitous Eddy (
伍ノ 型 月 魄 災 渦Go no kata: Geppaku Saika?) - Kokushibo makes multiple curved slashes layered over one another, resembling a rising vortex. Sanemi noted that Kokushibo performed this attack without swinging his blade.
- Sixth Form: Perpetual Night, Lonely Moon - Incessant (
陸ノ 型 常 夜 孤 月・ 無 間Roku no kata: Tokoyo Kogetsu - Muken?) - Kokushibo releases a wild barrage of crescent-shaped slashes in front of him. This technique was powerful enough to not only slice up multiple Hashira around him but also overwhelm the Wind Hashira Sanemi Shinazugawa.
- Seventh Form: Mirror of Misfortune - Moonlit (
漆ノ 型 厄 鏡・ 月 映え Shichi no kata: Yakkyō - Dzukibae?) - Kokushibo swings his sword in a powerful frontal slash that then creates a multi directional frontal assault, powerful enough to create several deep gouges in the ground and push back two Hashira.
- Eighth Form: Moon-Dragon Ringtail (
捌ノ 型 月 龍 輪 尾Hachi no kata: Getsuryū Rinbi?) - Kokushibo triples the range of his normal attack radius and creates a singular gigantic slash that slowly decreases in size.
- Ninth Form: Waning Moonswaths (
玖ノ 型 降り 月・ 連 面Ku no kata: Kudaridzuki - Renmen?) - Kokushibo creates a seemingly endless stream of claw-like vertical and horizontal slashes, capable of cutting down his intended target from a long range.
- Tenth Form: Drilling Slashes - Moon Through Bamboo Leaves (
拾ノ 型 穿 面 斬・ 蘿 月Jū no kata: Senmenzan - Ragetsu?) - Kokushibo creates a triple-layered slash twister, capable of mowing down his targets into three clean pieces.
- Fourteenth Form: Catastrophe - Tenman Crescent Moon (
拾 肆ノ 型 兇 変・ 天 満 繊 月Jū Shi no kata: Kyōhen - Tenman Sengetsu?) - One of the Moon Breathing's most powerful techniques. An advanced and more powerful version of Kokushibo's Fifth Form. He swings his sword and creates a chaotic vortex of powerful omni-directional slashes that destroys whatever is caught up within its attack radius.
- Sixteenth Form: Moonbow - Half Moon (
拾 陸ノ 型 月虹・ 片 割れ 月Jū Roku no kata: Gekkō - Katawaredzuki?) - Possibly the Moon Breathing's most powerful technique. Kokushibo creates a barrage of downward crescent slashes, resulting in a powerful sixfold slash crashing down on his opponents; the attack itself is powerful enough to create several miniature craters where the slashes have landed. As this technique is so wide-ranged, it is able to easily surround and overwhelm multiple enemies at once.
- Flesh Katana: Kokushibo harbors a fleshy and demonically modified version of a Nichirin Blade he used when he was a Demon Slayer. As suggested by its appearance, the katana is created from the flesh and blood of Kokushibo himself, and due to his body's phenomenal durability and hardness, his katana as well is as sharp and powerful, if not more, than a regular katana made of Nichirin. His blade his a fleshy red in color akin to the color of blood, with veins and his eyes all around his blade and even his hilt, it is unknown whether those eyes can be used to extend his vision, however, though it has been hinted at. His katana's hilt is circular shaped with 4 slight indentations, a center with 3 eyes and several black veins and a golden border. He also carries a scabbard to store his sword, which appears to be made of the same material as his katana. Kokushibo has a name for his katana which roughly translates to "Hollow Cry of the Godless".
- Kokushibo's name contains the kanji for "black" (
黒koku?), "death" ( 死shi?) and "eye" ( 牟bo?).
- He is the older twin brother of the Sun Breathing user who almost killed Muzan, Yoriichi Tsugikuni.
- Kokushibo is the first Demon Slayer to become a Demon.
- He became a Demon in his early 20s and lived as such for additional 460+ years.
- The relationship between Yoriichi and Michikatsu parallels the mythology of the Shinto deities Amaterasu and Tsukuyomi, respectively. Amaterasu is the most sacred of Shinto deities, the sun goddess. Tsukuyomi, the moon god, is her former husband and brother. After Tsukuyomi killed Uke Mochi, another shinto deity, Amaterasu refused to ever look upon him again, moving to another part of the sky and beginning the cycle of day and night. Like the deities, the siblings also feud and have chosen different paths (that of the Demon Slayer and the Demon), developing their respective breathings of the sun and moon.
- (In response to Muzan's reprimand) "I... have nothing... to say... Ubuyashiki... cleverly... hid... himself..."
- (To Akaza) "You... went too far..."
- (To Kaigaku) "Be thankful for the blood... You are not allowed to spill even a single drop on the ground... for if you do... your torso and head shall have a sorrowful parting."
- (In response to Akaza's death) "You opened a path... to reach further heights... and you abandoned it... Very weak."
- (In response to Yoriichi's statement about future generations) "Our generation alone was extraordinary. I was proud of the fact. And for someone like me, with such pride... I'd grow nauseous from the irritation and discomfort. What was so damn amusing?"
- (Thoughts before death) "Have I lived hundred of years for this?... Was I so afraid of defeat that I became a monster?... Did I want to be strong even if it meant eating people?... Did I become this miserable creature because I didn't want to die?... No... Yoriichi... I just... I wanted to be like you..."
- (Very final thought) "I could never grab hold... of anything. Anything at all. I abandoned my home. I abandoned my wife and children. I abandoned my humanity. I cut down my descendants... and abandoned being a samurai. But even all that... wasn't enough? You said that those who master their paths all reach the same place. But I never did. I could not see the same world that you did. Why could I not leave anything behind? Why could I not become someone known? Why are we so different? Why in the world was I ever born? Tell me... Yoriichi."