Kokushibo is a tall man with long black hair that he keeps in a ponytail. He has 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 wears 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 looks nearly the same as his current demon appearance, with the exception he has only two eyes, no additional eyes, he has eyebrows and his hairstyle slightly different than his current Demon appearance.
After being beheaded by Sanemi Shinazugawa and Gyomei Himejima, Kokushibo evolves into a grotesque version of his current appearance, with protruding fangs, a pair of horns, and several sharp appendages from his body.
Kokushibo is reserved yet shrouded in mystery. At the meeting of the Upper Moons, he is punctual, rule-abiding, and places a high value in the hierarchy of the Twelve Demon Moons. He is also humble, as he did not hesitate to admit his failure or complain of any difficulty, instead of acknowledging his opponent's strength. He has 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 is also rather cold; his words can be harsh, especially when reprimanding individuals. His threats come off as nothing short of cruel and overwhelmingly serious, and he demands absolute obedience.
He has a complex relationship with his human past. He shows something of warmth towards his descendant Muichiro Tokito, commending his skills and resolve, and moves to convert Muichiro into a demon to spare his life. At the same time, he refers to Muichiro and his abilities as the natural result of his "cells" being passed down. As a result, it is unclear whether he has any true attachment, or if it is the result of narcissistic pride. Seeing the two Demon Slaying Brothers, Sanemi and Genya Shinazugawa, makes him nostalgic. Battling Sanemi made him reminisce about dueling a former Wind Pillar to improve his skills. Later it was revealed that as a human he harbored an immense sense of jealousy towards his younger twin brother, Yoriichi Tsugikuni for his immense natural born talent and ability. These feelings of jealousy and eventual contempt were even further enhanced upon seeing his brother aged to an old man and having survived to this age despite awakening his Demon Slayer Mark, that 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 and loved his brother despite the negative views he held for him,as seen when he was genuinely touched by Yoriichi treasuring the handmade flute he had made for him as children and upon slashing his brothers corps and seeing that he still held on to the flute despite everything,Kokushibo shed genuine tears of regret over his brother 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 suggests a fear of death. When Gyomei's marks appear, Kokushibo preemptively bemoans the loss of a talented fighter and urges him to become a demon to continue honing his skills. He seems genuinely surprised when Gyomei vehemently rejects his offer and calls his mentality pathetic.
Likely a result of his inferiority complex and his immense desire for strength, Kokushibo fears the prospect of suffering defeat, so much that he becomes increasingly more aggressive and agitated when pushed further into a corner, and becomes more desperate in his attacks and the use of his demon power. During his battle with the pillars, he comes 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.
Born in the Sengoku Period, Kokushibo's birth name was Tsugikuni Michikatsu. At the time that he and his brother Yoriicchi were born, twins were considered a bad omen, and when their father saw that Yoriichi had a strange birthmark on his forehead, he declared that he would kill Yoriichi. However, his wife was outraged at his announcement, and an agreement was made that instead of being killed, Yoriichi would be sent to the temple and become a priest upon turning ten. Yoriichi and Michikatsu grew up very differently, Yoriichi being confined to a three-tatami room separate from the rest of the house and being kept away from his brother. Michikatsu, who had to sneak around behind their father's in order to see his brother, pitied Yoriichi, who was thought deaf until he was seven and clung to his mother's side whenever Michikatsu saw her. At some point, he gave Yoriichi a flute he made as a gift.
Around when Michikatsu was seven, he was practicing sword swings while his brother watched. It was then that Yoriichi spoke for the first time, shocking Michikatsu; however, Yoriichi's declaration of his goal to become a samurai like his brother was dismissed, as he would be sent to the temple when he was ten. Nonetheless, Yoriichi continued to watch Michikatsu's training, and one day, one of their father's men offered to give Yoriichi some instruction. Though he only showed him a basic stance, Yoriichi was able to land four blows on the man. This incident bewildered Michikatsu, who had never before landed a blow on the man, and he begged his brother to teach him his secret. To Michikatsu's disappointment, Yoriichi only expressed his distaste for combat and stated that he no longer wanted to become a samurai. Once, however, Yoriichi mentioned that before he took a stance, he breathed deeply, examining his bone alignment, muscle contraction, and blood flow, implying an early form of the Breath of the Sun style that Yoriichi would later adopt. This conversation caused Michikatsu to realize that for Yoriichi, the bodies of living things were transparent, causing him to pursue mastery of the blade with renewed intensity.
As Michikatsu studied the sword, he felt envious of his brother, who he felt was squandering his natural physical talent. He also feared that, now that their father likely knew about Yoriichi's immense potential, their roles would be swapped and he would be the one sent to the temple in Yoriichi's place. Yoriichi recognized this as well; the night that their mother finally succumbed to her illness, he came to Michikatsu's room at three in the morning to tell his brother the news and bid goodbye to Michikatsu, as he planned to leave for the temple before their father could make Yoriichi the family's new successor. Yoriichi expressed gratitude to his brother for giving him heart and fondly held the flute that Michikatsu had given him earlier. Michikatsu, however, was irritated, wondering how Yoriichi could treasure a flute that couldn't even play in tune, and watched his brother depart while saying nothing. His jealousy of his brother only grew when he read his mother's diary following her death, which revealed that Yoriichi had known everything about their mother's illness from when she would die and the increasing weakness of the left side of her body, and had planned accordingly. From then, Michikatsu resented Yoriichi, who he realized to be not only physically gifted, but a genius as well.
Ten years later, Michikatsu became a samurai and married a woman who gave birth to two of his children. One night, a demon attacked his camp, but was quickly killed by Yoriichi who came to his rescue and apologized for not being able to save his subordinates. Twisted by jealousy, Michikatsu abandoned his family and became a Demon Slayer by training under Yoriichi. During that time, he trained alongside a Breath of Wind user and polished his sword skills together with them. Eventually, Michikatsu awakened a Demon Slayer Mark and developed a Breath Style derived from the Breath of the Sun known as the Breath of the Moon. Frustrated from being unable to surpass his brother, as well as fearing the fated death of those who awakened their Demon Slayer Marks, Michikatsu was persuaded by Muzan Kibutsuji and became a demon. 
As a Demon Slayer, Michikatsu was often prideful in the uniqueness of their generation, but was irritated by his brother's optimism when he brought up the fact that the pair had no successors in line for their unique Breath Styles, the Breath of the Sun and Breath of the Moon.
Out of fear of death, Michikatsu became a Demon and took on the name Kokushibo. Because he was also Breath user, it took him three days fully transform into a demon. Eventually, he became Upper Moon One of the Twelve Demon Moons, remaining at that rank for hundreds of years, while his original name was lost to history.
Sixty years after becoming a Demon, Kokushibo comes face to face with Yoriichi, his brother. Yoriichi offered his sympathies at the fact that Kokushibo is now a Demon and that he must slay him. Yoriichi then completely outclasses Kokushibo, even slitting his throat. Kokushibo remembers their past together, angrily yelling how the Gods always smiled upon him and how he was blessed with otherworldly skill as a swordsman. Even letting him live to old age while all other marked individuals would die by the age of 25. But, before Yoriichi had the opportunity to cut Kokushibo's head entirely off, he dies standing due to old age. Enraged by the feeling of inferiority, Kokushibo slashed Yoriichi in half, along with the flute he gave him as a gift. However, it is later revealed that he still kept the flute, being unable to truly sever his bond with his brother.
Having fought numerous Demon Slayers across the centuries, he encountered one Demon Slayer about 300 years prior to the present with an ability similar to Genya's-devouring demons to enhance his own strength. It is implied that this Demon Slayer's ability wasn't as adapt as Genya's given that Kokushibo slew him just by cutting his torso into two.
Kokushibo was summoned to a meeting of the Upper Moons, arriving before all of his colleagues. He silently sat facing a wall; only speaking when his presence was acknowledged by the Biwa Demon, and revealing that Muzan had arrived. Muzan revealed the death of Gyutaro, berating Kokushibo and his fellow Upper Moons for being unable to destroy the Ubuyashiki family and failing to find the Blue Spider Lily. Kokushibo admitted that he had nothing to say in his defense, as Kagaya Ubuyashiki had cleverly hidden himself.
After Akaza brutally destroyed Doma's head, Kokushibo covertly sliced off the former's hand, stating he had gone too far. He explained to Doma that he had not intervened for his benefit, but for the preservation of the hierarchy of the Upper Moon system. He then told Akaza to arrange for a blood battle if he wanted to take Doma's position, asking him if he understood what he was being told. Akaza acknowledged this fact; promising to kill the high-ranking Upper Moon, which Kokushibo wished him luck before departing.
Kokushibo is present in a flashback of Kaigaku, depicting the time just before Kaigaku following his defeat at the hands of Kokushibo. Kokushibo then offers his own blood and the power that Kaigaku craves if "that man" is willing to accept him as an ally. And as he does, he threatens that if a drop of blood is spilled, the human will be beheaded.
Following Akaza's death, Kokushibo is seen alone. Murmuring how Akaza had abandoned his path to reach further heights and how he had failed to defeat Kokushibo, and reprimanded him for how weak he is. Simultaneously, he reaches for his katana, and instantly slices the surrounding stone pillars to pieces in a single stroke.
Some time later, Muichiro Tokito is transported to the same room as Kokushibo. Kokushibo then comments: "You came... Demon Slayer. For some reason... you seem familiar". He then deduces that Muichiro is a descendant of a child he left behind after becoming a demon. He also deduces that his human surname of Tsugikuni has died out over the generations. After Muichiro calms himself down and performs various Styles from the Breath the Mist, his Demon Slaying Mark appears. Kokushibo then complements how accomplished Muichiro is as a swordsman at such a young age. Kokushibo states that it must be due to the powerful blood he passed down, although Muichiro dismisses such claims. After some more battling, Kokushibo manages to cut off Muichiro's arm. Muichiro quickly tightens his arm to stop the bleeding, greatly impressing Kokushibo. However, he is effortlessly pinned against a pillar. Kokushibo then offers Muichiro the opportunity to become a demon who is faithful to Muzan. Stating that this would not only heal his arm, but also offer him great power.
This discussion is however interrupted by Genya shooting his Nichirin Gun. Kokushibo easily avoids the gunshot, appearing behind Genya and then proceeding to cut off both his arms and his torso in half, commenting that: "Hmm, I see. You're the one who's been eating demon's, huh?" However, he realises that Genya is unlike the other imitation demon from 300 years ago and that the way to kill him is the same way regular demons are killed, by chopping off their head. Before he has the opportunity to do this, Genya is saved by his brother. After Genya apologises for everything he's done to Sanemi, Kokushibo states that: "Hmm, brothers and Demon Slayers, that brings back memories...". Given this and his appearance, it is heavily implied that he might be the brother of the man who passed the Dance of the Fire God down to the Kamado family.
Sanemi and Kokushibo then begin their intense duel, with Kokushibo being slightly taken aback at the skill of the Wind Pillar. However, he retains his composure and stated that he couldn't survive if his senses weren't honed from long experience. This goes on for sometime, with Kokushibo even stating that long ago when Japan was at war, he gained a lot of experience fighting against a similarly strong Wind Pillar. Kokushibo then gets a good enough cut on Sanemi, stating that moving would lead to his entrails to spill out. Sanemi proceeds to laugh hysterically, boasting the fact that he had marechi blood. Sanemi uses his abnormal body and breathing skills to control his muscles to coagulate the blood and stop the bleeding as much as possible. After some struggling and Kokushibo showing glee at the opportunity at fighting such a skilled Pillar, he was about to deal a significant blow until Gyomei, the Stone Pillar arrives.
Kokushibo was unable to retain himself. Openly stating that he admired Gyomei's peek physical form. Following an intense back and forth battle, Gyomei reveals his trump card he meant to save for Muzan, his Demon Slaying Mark. Kokushibo then confirms that he too has the Demon Slaying Mark. Almost showing sympathy towards Gyomei, he reveals the caveat of the Demon Slaying Mark: "Without exception, the marked ones die before they reach the age of 25." Stating that the mark reduces life expectancy and that Gyomei should be dead by the end of the night since he's 27 years old. After an existential discussion of what it means to be a Demon Slayer and a human, Kokushibo offers Gyomei an opportunity to become a demon so he can survive and continue to hone his craft the same way he has. Gyomei outright rejects the offer and states that Kokushibo stated one falsehood: "I suspect there was an exception. There was one who had the mark, lived past 25 and is still alive." Kokushibo then appears to be somewhat shaken, but the two continue their intense battle. After Sanemi manages to stitch his wound, he rejoins the fray as the two now face Kokushibo in a 2 on 1 battle. Kokushibo notes with surprise the ease with which they are able to cooperate despite being users of two different breaths . The three of them continue their battle until suddenly, Sanemi and Gyomei are cut by what appears to be an elongated sword with three blades extending from the sides, two from one side and one on the other. Kokushibo now appears to be completely serious in his encounter, angrily stating: "You merely shredded my kimono, not even enough to kill an infant. Once I dispatch you two, the rest will proceed easily."
In the meantime, Muichiro manages to free himself from the pillar. With the little life left in him, he helps Genya by reattaching his body and feeding him a clump of Kokushibo's hair. Genya then feels power he's never felt before, but more importantly appears to directly hear Muzan's voice, asking Kokushibo: "Kokushibo, how many Hashira have you defeated? Don't let them come here yet.", indicating that Muzan is likely still incapacitated by the initial explosion and the Blood Demon Art Tamayo performed on him.
The battle then begins to pick up, Kokushibo's attacks increasing with both intensity and frequency. He is able to sever two of Sanemi's fingers, and Gyomei and Sanemi are both reduced to putting all of their efforts into simply avoiding his attacks. Right as it seems that Sanemi is about to lose, though, Muichiro rejoins the battle, saving the other Pillar just in time . Genya, who is hiding from the battle behind a wall, recalls a conversation he had with Tanjiro about being the weakest person in a battle, and, motivated by this, swallows a broken piece of Kokoshibo's blade in order to gain its abilities. The advantage seems to again shift to Kokoshibo, but in an unexpected turn of events, Gyomei is able to sever the Upper Moon's right arm while Muichiro stabs him through the torso, immobilizing him while Genya unleashes a barrage of bullets on the demon using his gun, which he altered using his own cells in a similar manner to Kokushibo's sword. The bullets embedded into the Demon's flesh then erupt into "trees," completely trapping him as Gyomei and Sanemi rush in to finish him off. The sensation disturbs Kokushibo, who is reminded of an encounter from 400 years ago in which he met his younger brother, Yoriichi, after not having seen him for 60 years. In the encounter, Yoriichi was able to land a hit on his brother's neck, which no one had ever done before; however, Yoriichi passed away on his feet before he was able to land the next blow.
Enraged by the thought of being defeated, Kokushibo sprouts many blades from his body and slashes both Muichiro and Genya in half (Muichiro horizontally, Genya vertically) and severely wounding Sanemi and Gyomei. Still, the four charge onwards, undeterred. As Muichiro's blade turns red, seeming to sear Kokushibo's organs, Genya unleashes another Blood Demon Technique, rooting another tree in Kokushibo's back while Gyomei lands a blow on Kokushibo's head with his flail and Sanemi rushes in with his sword. Their weapons all begin to turn red, and, struck with thoughts of his brother, Kokushibo marvel at how the Demon Slayers who came after them have risen up to surpass them. However, wonder soon gives way to rage as Kokushibo's head is cut off, and, to the horror of the four Demon Slayers, Kokushibo regrows his head.
Kokushibo begins to celebrate, boasting to himself that now that he has conquered death by beheading, any attacks thrown at him are now rendered meaningless. However, his triumph gives way to disbelief when he sees himself in the reflection of Sanemi's blade. His new form is monstrous, with tusks and spikes of flesh protruding from his head face and back. Stunned by his appearance, he recalls his original motivation to be the strongest samurai in the country and wonders if the path he has taken is what he really wanted. While he reflects on his motivations, Gyomei is able to crush his head with his flail, again beheading Kokushibo. The Upper Moon attempts to regenerate, but to his disbelief, his flesh begins to crumble away and he is rendered unable to use his Blood Demon Technique. As he falls to the ground, disintegrating, he reflects bitterly that he only wanted to be like Yoriichi while his life flashed before him. In the end, he admits that he abandoned everything and got nothing from it. In fact, he killed his only remaining blood relative and betrayed his samurai code. He then crumbled away completely, leaving only the sliced up pieces of flute he made for Yoriichi when they were children, which he kept for all these centuries.
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.
- 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 then 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 higher 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", 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 monsterous 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.
- Flesh Sword: 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 - Moonlit (
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: Moon-Dragon Ringtail (
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: Waning Moonswaths (
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: 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.
- Eleventh Form:
- Twelfth Form:
- Thirteenth Form:
- Fourteenth Form: Catastrophe - Tenman Crescent Moon (
拾 肆ノ 型 兇 変・ 天 満 繊 月Jūshi no kata: Kyōhen - Tenman Sengetsu?): 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: Moonbow - Half-Broken 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..."