Kokushibo was a tall man with long black hair that he keeps in a ponytail. He had three sets of eyes on his face, with red-eye whites and yellow irises. His middle set of eyes features the mark of Upper Moon One, and red markings resembling flames can be seen on his face and neck. He wore a patterned kimono with a black hakama on his waist. On his waist, he carries a sword that has 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.
Kokushibo's appearance as a human looked nearly the same as his demon appearance, with the exception of the number of his eyes, his eyebrows and his hairstyle.
After being beheaded by Sanemi Shinazugawa and Gyomei Himejima, Kokushibo evolved into a grotesque version of his previous 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 Demon Moons, 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 Demon Moons - as seen at the Upper Moon Gathering . Kokushibo was portrayed as 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 he harbored an immense sense of jealousy 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, it was shown that he still deeply cared for and loved his brother - as seen when he was genuinely touched by Yoriichi treasuring the handmade flute he had made for him as children. Kokushibo shed genuine tears of regret over his brother after murdering him and even went as far as keeping the flute itself for the next hundred years as a memento to the younger brother he both hated and loved.
In his duel against Gyomei Himejima, his banter suggested a fear of death. When Gyomei's marks appear, Kokushibo preemptively bemoaned the loss of a talented fighter and urged him to become a demon to continue honing his skills. He seemed genuinely 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 pillars, he came to realize the steep price he has 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 have 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.
Abilities and Powers
Kokushibo is an extremely powerful swordsman, considered to be the strongest of the Twelve Demon Moons and the second strongest demon in the series, just behind Muzan Kibitsuji. As one of the oldest demons in the series, he has battled numerous Demon Slayers and has obtained vast experience and knowledge of combat. He was able to easily decipher the techniques and skills of at least two Pillars and overwhelm them in battle. As a breath user, he possess tremendous levels of strength and reflexes that are further enhanced by his demon physiology.
These overall abilities and skills allowed him to defeat two Pillars with minimal effort and then fight on par against Gyomei, who is considered to be the most powerful Demon Slayer in the Demon Slaying Corps. Even when Gyomei and Sanemi awaken their demon slayer marks which increase one's physical abilities way above their normal limit, he is still capable of holding his own against the both of them simultaneously.
When he starts using his more of his power, he manages to overwhelm both Gyomei and Sanemi, both of whom were boosted by their Demon Slayer Marks. Testament to his might, it ultimately took a combination of attacks from Gyomei, Sanemi and Muichiro to even land a significant injury on him.
In the end, Kokushibo's loss against the Pillars was mostly a result of him losing the will the continue fighting, rather than the skills of his opponents.
- Master Swordsman: Kokushibo is an extremely powerful and skilled swordsman. During his time as a human, he was one of the first Breath users.
- Immense Speed: Kokushibo possesses immense levels of speed, as shown when he outpaces Muichiro's Breath Techniques with great ease. Muichiro himself states that Kokushibo's speed is in another dimension compared to the Pillars.
- Immense Durability: Kokushibo has 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 head to slide down Gyomei's Axe.
- 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 is Kokushibo no longer bound by the curse, but the Mark's abilities are enhanced even further than when he was a human.
- See-Through World (
透き 通る 世 界Sukitōru Sekai?): Similar to Tanjiro, Kokushibo has obtained the ability to see the "see through 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 he was able to see that Genya consumed demons to gain strength by looking into his cellular structures.
- Enhanced Regeneration: Kokushibo possesses incredible regeneration, able to regenerate his ear and right arm getting cut by Gyomei with no effort. Later, upon being decapitated by two Pillars, Kokushibo was able to regenerate his entire head and successfully conquered death by beheading, a feat only accomplished by only two Demon in existence; Akaza and Muzan. However, the process was slower than with Muzan and more unstable than Akaza, causing him to take on a monstrous visage.
- Demonic Transformation: Later, upon regrowing his head while battling Gyomei and Sanemi, Kokushibo was able to transform himself into a demonic, monstrous form resembling a spider that presumably enhances all of his abilities and powers.
- Enhanced Breath Techniques: As a Demon, Kokushibo's Breathing Techniques has been enhanced to heights beyond even what Pillars can achieve. His former position as analogous to a Pillar prior to becoming a Demon, as well as his Demon Slayer Mark and being an Upper Moon, shows that his skill and efficiency with Full Focus Breathing is almost unparalleled, with only his naturally-gifted brother surpassing him.
- Blood Demon Technique (
血 鬼 術Kekkijutsu?): - Flesh Sword: Although the specific name of the Blood Demon Technique is unknown, Kokushibo reveals that he had detached some of his own flesh and shaped it into the katana that he uses in battle. The blade possesses numerous eyes in the blade, handle, and guard, allowing him to have an increased range of vision while using it in battle. Also, since the blade is created from his flesh, the blade can 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. 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 Pillars and destroy Genya's Blood Demon Art Technique, 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.
Breath of the Moon (
- First Form: Dark Moon - Evening Palace (
壱ノ 型 闇 月・ 宵の 宮Ichi no kata: Yamizuki - Yoi no Miya?): Kokushibo draws his sword and slashes swiftly in a single motion, like with all Breath of the Moon techniques, numerous chaotic crescent shaped blades originate from the slash. This technique resembles Iaido.
- Third Form: Loathsome Moon - Chains (
参ノ 型 厭 忌 月・ 銷り San no kata: Enkizuki - Tsugari?): Kokushibo swings his sword rapidly in two crescent slashes, from which a storm of smaller crescents spread. This technique causes huge destruction in a small area.
- Fourth Form:
- 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. Numerous chaotic blades originate from these slashes. 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 storm of slashes in multiple directions. This technique was powerful enough to not only slice up multiple Pillars around him but also overwhelm the Wind Pillar Sanemi Shinazugawa.
- Seventh Form: Mirror of Misfortune - Lunar Shine (
漆ノ 型 厄 鏡・ 月 映え Shichi no kata: Yakkyō - Zukibae?): Kokushibo swings his sword in a powerful frontal slash that then creates a multi directional frontal assault, powerful enough to create several deep craters in the ground and push back at least two Pillars.
- Eighth Form: Lunar Ouroboros (
捌ノ 型 月 龍 輪 尾Hachi no kata: Getsuryū Rinbi?): Kokushibo uses a direct frontal attack that creates a single gigantic slash.
- Ninth Form: Descending Moon-Perpetual Phases (
玖ノ 型 降り 月・ 連 面Ku no kata: Kudarizuki Renmen?): Kokushibo creates a seemingly endless stream of slashes capable of cutting down his intended target from long range.
- Tenth Form: Piercing Phase Slash-Ivy Moon (
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.
- Eleventh Form:
- Twelfth Form:
- Thirteenth Form:
- Fourteenth Form: Calamity: Heaven's Full Crescent Moon (
拾 肆ノ 型 兇 変・ 天 満 繊 月Jūshi no kata: Kyōhen - Sainan: Tengoku no mikadzuki?): Kokushibo swings his sword and creates a chaotic vortex of powerful omni-directional slashes that destroys whatever is caught up within its attack radius.
- Fifteenth Form:
- Sixteenth Form: Lunar Rainbow- Half Fragmented Moon (
拾 陸ノ 型 月虹・ 片 割れ 月Jūroku no kata: Gekkō - Katawarezuki?): Kokushibo brings down a downward slash that then produces 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.
- Kokushibo is the older twin brother of the Breath of the Sun user who almost killed Muzan, Yoriichi Tsugikuni.
- Kokushibo is the first Demon Slayer to become a Demon.
- Kokushibo became a Demon in his early 20s and lived as such for additional 460+ years.
- (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."
- (Last Thought 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..."