History Characters / DemonSlayerKimetsuNoYaibaKokushibo

* PerpetualFrowner: Almost never do we see Kokushibo smile.

Upper-1. [[TheDragon Muzan's partner and right-hand man]], he has occupied the position of Upper-1 for at least 400 years. Unlike many other demons, he eschews relying upon his supernatural powers and focuses on perfecting his swordsmanship, the likes of which is unmatched by anyone alive. Because of his rank, [[WorldsStrongestMan he's heavily known as the second strongest demon in the whole series]], only next to his master.

* TheAce: The top Upper Rank and the scariest, as well as the most skilled. How scary and skilled? His descendant Muichiro is considered TheAce of the Hashira with the most innate potential, and proved it by killing Upper-5 Gyokko after his training to unlock his Demon Slayer Mark easily and by himself, a feat considered nigh-impossible. Kokushibo absolutely ''thrashes'' Muichiro in their one-on-one while taking no damage himself.

** Also acts as one to Genya. Genya is a human who uses demon arts, while Kokushibo is a demon who uses a breathing style, both resorted to using the power of demons to become stronger than their more-skilled brothers, and both use nonstandard weaponry for their respective roles. They differ in that Genya is a JerkWithAHeartOfGold [[PoliteVillainsRudeHeroes while]] Kokushibo is AffablyEvil. Additionally, while both sought to become as strong as their brothers, Genya never went as far as to ally with [[BigBad Muzan]] himself, nor never feeling envious towards Sanemi. In the end, they both die [[NoBodyLeftBehind similar deaths]], but while Kokushibo falls in utter despair, desperately wishing he could talk to Yoriichi, Genya reconciles with Sanemi in his final moments, his last words being a heartfelt DyingDeclarationOfLove.

** Acts as one to Genya. Genya is a human who uses demon arts, while Kokushibo is a demon who uses a breathing style, both resorted to using the power of demons to become stronger than their more-skilled brothers, and both use nonstandard weaponry for their respective roles. They differ in that Genya is a JerkWithAHeartOfGold [[PoliteVillainsRudeHeroes while]] Kokushibo is AffablyEvil. Additionally, while both sought to become as strong as their brothers, Genya never went as far as to ally with [[BigBad Muzan]] himself, nor never feeling envious towards Sanemi. In the end, they both die [[NoBodyLeftBehind similar deaths]], but while Kokushibo falls in utter despair, desperately wishing he could talk to Yoriichi, Genya reconciles with Sanemi in his final moments, his last words being a heartfelt DyingDeclarationOfLove.

[[quoteright:739:https://static.tvtropes.org/pmwiki/pub/images/kokushibo.jpeg]]

[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/kny_kokushibo_anime.jpg]]

* LonelyAtTheTop: Kokushibo went as far as to become a demon in his relentless pursuit of being WorldsStrongestMan, but it came at the cost of losing the relationship with his wife, child and brother.

* LyingToProtectYourFeelings: Essentially did this ''to himself''. e's spend a good part of his life relentlessly telling himself that he hates his twin Yorichii down to his core. In truth he has a complicated sense of brotherly love for him and he greatly mourns his passing, not to mention he still keeps a memento of him well over 300 years after he died. He does this because accepting it would mean that half of his reason for becoming a demon and sacrificing everything to preserve and perfect his craft was a complete waste of time that he didn't even truly wanted to do. The moment he comes to terms with the fact that he lived out of jealously and a rivalry he didn't truly believe in he asks himself what was even his worth in life and he stands still as the demon slayers maul him to death.

* MonstrousCannibalism: According to the 2nd Databook he has consumed other demons in a display of utter dominance over those below him, particularly doing so against demons who tried to challenge him for his Upper Rank 1 spot; the only one who Kokushibo hasn’t eaten after daring to fight him is Akaza, Kokushibo really held high hopes for the Upper-3 to become a suitable rival towards him, allowing Akaza to challenge him several times throughout the years.

* AllForNothing: Selling his humanity to become the strongest and becoming a monster? He never could surpass Yoriichi and simply becomes one of the monsters that he once hunted. He realized that all of those centuries of trying to be the undefeated swordsman led to nothing beneficial for him.

** Determination. Kokushibo is determined to win and he will not go down easily. Even after being decapitated, he used his sheer will to completely regenerate his head to conquer death. If he didn't see what he became, he wouldn't lose his will to fight.

* {{Irony}}: Muzan's greatest servant and one of the most dangerous Kizuki to ever live was a Slayer in his human life, and is implied to have secured his status as such using the Demon Slayer Mark and Transparent World technique he originally mastered for the sake of ''hunting'' demons.

* NamesToRunAwayFromReallyFast: Kokushibo derives his name from the Japanese word for TheBlackDeath. He is one of the few demons who clearly remembers their past lives as human beings, including their previous name, Michikatsu Tsugikuni, so it seems he willingly took that name.

* NotSoStoic: Kokushibo, when pressed, begins shedding his stoicism, letting loose ear-splitting roars of fury.

* TheStoic: Nothing phases him at all. Not death threats from a subordinate, not Muzan contemplating exterminating the Twelve Kizuki, not a death battle. [[NotSoStoic But when it comes to Yoriichi or when he gets too pressed in battle, that's a different story.

* VillainRespect: After discovering that Muichiro is his direct descendant and analyzing his fighting skills, he gives him great respect and [[WeCanRuleTogether even offers him to become a demon and join Muzan's army if Muzan allows it.]] But he gives the greatest respect to Himejima, who he claims is the strongest Hashira he has fought in over 300 years, and attempts multiple times to persuade Himejima to become a Demon so that he can preserve his techniques since the Demon Slayer Mark will kill him by the end of the night.

* HisOwnWorstEnemy: The tragedy in his human life comes from a succession of choices he made and had no one else to blame but himself, unlike several of his fellow Kizuki members who suffered under completely external factors.
Michikatsu chose to harbor jealousy over Yoriichi's talent which nurtured a massive inferiority complex, to the point he created his own false memories of absolutely hating Yoriichi over the centuries in order to force himself to believe his choices were valid, not petty; Michikatsu chose to abandon the life as the head of the Tsugikuni family, leaving his wife and children behind to pursue strength under Yoriichi's teachings; Michikatsu chose to betray the Demon Slayer Corps with the growing fear of dying under the effects of the Mark and wasting all the years he gave into perfecting his martial arts, turning into the demon Kokushibo to retain all of it. As Kokushibo is about to die he is left with nothing but regrets, coming to terms all of his efforts to remain alive as a demon led to absolutely nothing truly beneficial to him, and he just couldn't hate Yoriichi as much as he believed he did, wondering why he was even born.

[[/folder]]

'''Warning: Kokushibo is a WalkingSpoiler, so all entries for this character are unmarked.'''

** Acts as one to Genya. Genya is a human who uses demon arts, while Kokushibo is a demon who uses a breathing style, both resorted to using the power of demons to become stronger than their more-skilled brothers, and both use nonstandard weaponry for their respective roles. They differ in that Genya is a JerkWithAHeartOfGold [[PoliteVillainsRudeHeroes while]] Kokushibo is AffablyEvil. Additionally, while both sought to become as strong as their brothers, Genya never went as far as to ally with [[BigBad Muzan]] himself, nor never feeling envious towards Sanemi. In the end, they both die [[NoBodyLeftBehind similar deaths]], but while Kokushibo falls in utter despair, desperately wishing he could talk to Yoriichi, Genya reconciles with Sanemi in his final moments, his last words being a heartfelt DyingDeclarationOfLove]].

* TheAce: The top Upper Rank and the scariest, as well as the most skilled. How scary and skilled? [[spoiler:His descendant Muichiro is considered TheAce of the Hashira with the most innate potential, and proved it by killing Upper-5 Gyokko after his training to unlock his Demon Slayer Mark easily and by himself, a feat considered nigh-impossible. Kokushibo absolutely ''thrashes'' Muichiro in their one-on-one while taking no damage himself.]]
* AffablyEvil: Unlike Akaza, who isn't above trash talking, or Doma, who constantly teases and mocks his opponents, he is very polite and well mannered, as well as sincere, even if he doesn't speak much. He doesn't spare compliments for his opponents either, praising their skill on several occasions. [[spoiler:Considering he basically sacrificed his own humanity to conserve and perfect his skills as a swordsman, it makes sense he values and respects dedication to the craft in others.]]
* AlasPoorVillain: [[spoiler:As he lays dying, he realizes that he ultimately wasted his entire life pursuing an inferiority complex against his brother, even though the latter never bore any grudge against him. His last thoughts are asking why he was even born.]]
* AllForNothing: [[spoiler:Selling his humanity to become the strongest and becoming a monster? He never could surpass Yoriichi and simply becomes one of the monsters that he once hunted. He realized that all of those centuries of trying to be the undefeated swordsman led to nothing beneficial for him.]]
** His selfish quest for greatness and the jealous way he guarded the techniques of both his family and those of his own invention ensure that [[spoiler:his knowledge dies with them, forgotten and irrelevant.]]
** In a twisted case of irony, [[spoiler: he initially spares Muichiro's life with the intention of turning him into a demon, as he is pleased that his bloodline lived on even after his transformation. He eventually ends up slaying him later on, ending his bloodline for good.]]
* AlwaysSecondBest: He lived his life in the shadow of his twin [[spoiler:Yoriichi. He was never, ever able to surpass him or learn the Sun Breathing]]. Ironically, even now, he's only the second strongest being, as Muzan is still over him.
* AlwaysSomeoneBetter: For Kokushibo, it was[[spoiler: his younger twin brother Yoriichi, who he could never surpass. Even as an immortal demon, and with Yoriichi an old man, Yoriichi still proved to be the superior between them.]]

* ArchEnemy: [[spoiler:Twisted all over the place in his relationship with his younger twin brother, Yoriichi Tsugikuni. While Yoriichi always admired his brother and considered him a good person, Kokushibo was extremely jealous of Yoriichi's natural talent, which he could never measure up to despite endlessly training, and a significant portion of his motivations centers entirely around his inferiority complex regarding his brother. He insists to himself that he thoroughly detested Yoriichi, including but not limited to describing himself as "blazing with hatred" for him and mentally begging him to die. However, it's clear that this is a case of an UnreliableNarrator (regarding his own backstory, no less). In spite of his envy for Yoriichi, Kokushibo loved his brother deeply, shedding tears over his death and moved by the realization that Yoriichi had kept the flute that he gave him when they were children and continued thinking highly of him even after he became a demon. After Yoriichi's death, he was unable to part with the flute and kept it on his person until his own demise several centuries later. Furthermore, it is remembering Yoriichi's words to him that made Kokushibo falter upon realizing how hideous he'd become in his pursuit of strength, and the last person he calls out to as he disintegrates his brother, asking him why he was ever born, of all things.]]
* {{BFS}}: [[spoiler:It turns out his regenerating katana can grow longer and sprout multiple smaller blades out of its main blade. It also counts as an OddlyShapedSword due to adding extra blades on its blade.]]
* BigBrotherWorship: [[spoiler:Inverted. In his final moments, he remembers that all he wanted was to be like his younger twin brother, Yoriichi. Ironically, Yoriichi has this toward him as well, deeply respecting and loving his older brother even after he chose to become a demon.]]
* BodyHorror: [[spoiler:His monstrous spider-like form in chapter 176 is shown to be very disfigured. His head has all six of his eyes staring in all directions, and he grew a snout full of sharp and crooked teeth sprouting everywhere. Upon seeing his reflection on Sanemi's blade, even he is disgusted by this form.]]
* BrokenAce: [[spoiler: Despite his strength and talent, he was always surpassed by his younger twin brother and because of that, it caused him to become [[GreenEyedMonster envious and jealous towards him]] and besides that, he feared the possibility of defeat and death, so he went as far to become a demon to avoid that. Despite this, he nearly gets killed by Yorrichi who was a dying elderly man. The fact Yoriichi dies of old age instead of dying in battle enraged Kokushibo since that makes Yorrichi an undefeatable warrior, something that Kokushibo wanted to become. But now with Yoriichi dead, [[InferioritySuperiorityComplex Kokushibo's pitiful inferiority complex]] continues to worsen for him]].
* CainAndAbel: [[spoiler:Chapter 174 reveals that he is the eldest twin brother to Yoriichi Tsugikuni, the Sun Breathing user. He became jealous of Yoriichi because he had much greater natural talent and skill than he could ever compete with, even though he was taught daily in swordsmanship while Yoriichi had not trained a day. He was even astonished that his brother managed to survive with a Demon Slayer Mark during their battle 400 years ago and that even at the age of 85, Yoriichi's skill and physical prowess hadn't dulled in the slightest.]]
* ClimaxBoss: The showdown with him reveals key elements of the series lore, [[spoiler:and it also marks the ending of the Twelve Kizuki, who had been the most prominent antagonist up to that point. Suitably, once Kokushibo is defeated, Muzan himself takes center stage]].
* ClippedWingAngel: [[spoiler:What his spider demon form turns out to be. His frustration at his brother's beliefs and the strength of the Demon Slayers gives him the determination to not lose, forcing himself to regenerate despite being beheaded like Akaza. However, unlike Akaza's subconscious drive to protect his loved ones, Kokushibo's determination is fueled by a combination of jealously, obsession and desire to avoid death, so this ends up being a highly unstable, monstrous spider-like form. On top of this, it took a lot of energy for him to NoSell his beheading and his regeneration slowed down considerably as a result. Kokushibo’s grotesque appearance also leads to the demon having a WhatHaveIBecome moment when he sees his reflection, and his drive to fight dies off.]]
* ClothingDamage: [[spoiler:He loses his haori to Himejima and Sanemi's combination attack, leaving him topless.]]
* TheCoatsAreOff: [[spoiler:He already seemed to be too much trouble with his clothes fully on. Kokushibo was making three Hashiras (Muichiro, Himejima, and Sanemi) break a sweat against him. Then, Himejima and Sanemi manage to rip Kokushibo's haori (coat) off, and that's where Kokushibo stops playing around. Himejima and Sanemi went from trying to go on the offensive to then struggling just to not die against Kokushibo's devastating long-range attacks]].

* TheCorrupter: Kokushibo converts Demon Slayers over to Muzan's side by overwhelming them with his power and then forcing them to drink Muzan's blood, turning them into demons themselves. He recruited [[RivalTurnedEvil Kaigaku]] this way and would have done the same [[spoiler:to Muichiro if Genya and Sanemi haven't intervened. He himself was a victim of this by Muzan who preyed on his insecurities to convince him to become a demon.]]
* CurbStompBattle: [[spoiler:He absolutely ''dominates'' his descendant Muichiro in their one-on-one fight, overwhelming him even better than how Muichiro in turn had managed curb-stomp Gyokko in their own rematch.]]

* DespairEventHorizon: He gave in to total despair, realizing his Mark would kill him, and he'd never be able to grow beyond Yoriichi. [[spoiler:Muzan takes full advantage of this and easily convinces him to become the demon Kokushibo.]]

* DisappearedDad: He is one, [[spoiler:Kokushibo doesn’t mince words when recalling his past life as the human Michikatsu, at the time he was seemingly the happiest as the head of the Tsugikuni family with a wife and children to care for, but upon unexpectedly reuniting with Yoriichi after so many years, upon being saved by Yoriichi in a losing battle against demons no less, reignited his desire to grow stronger as a warrior; with that Michikatsu simply abandoned his family to pursue strength for himself, a fact that only got worse after he betrayed the Demon Slayer Corps to serve Muzan as the demon Kokushibo; that little unexplored fact certainly destroyed the Tsugikuni family over the centuries, seeing how his known descendants were just a poor family of lumberjacks living in the mountains, compared to another prestigious family from the Golden Age of Demon Slayers, the Rengoku family, remaining intact in their notoriety]].

* TheDreaded: As the second strongest demon, his power and aura is so terrifying that it would even make the other Upper Ranks tremble in fear. When first meeting him, Muichiro Tokito, a Hashira [[spoiler: who had faced an Upper Rank on his own in the past and won]], was shaking with fear, to the point of even nearly losing his will to fight against Kokushibo.
* DyingAlone: [[spoiler:Upon death Kokushibo shamefully joins the ranks of demons who have died without anyone being there for him in the afterlife, the sign of karma for abandoning everyone that had cared for him; Kokushibo is seen being [[DraggedOffToHell forcefully dragged into hell]] alone on Chapter 179's cover page]].
* EvenEvilHasLovedOnes: A powerful and ruthless demon, but he still remembers his human children very fondly and [[spoiler: is pleased to learn his family's bloodline eventually produced another MasterSwordsman in Muichiro. And although he hated his brother Yoriichi, he still had a complicated sense of brotherly love for him. Additionally, part of his hatred for Yorichii is more of a fabrication by himself, as Yorichii's own backstory directly mentions that Michikatsu was never mean or unfriendly to him.]]

* EvilTwin: [[spoiler: He's the oldest twin brother of Yoriichi Tsugikuni, and is the second strongest demon in the series]].

** [[VillainRespect Respect]]. Despite being a highly powerful demon, second only to his master, Kokushibo doesn't completely look down on humans, having a slight degree of respect for them (as far as wanting them to become demons, however, as seen with [[spoiler:Muichiro]]). [[spoiler: For example, he respected Muichiro, Genya, Sanemi, and Gyomei for their skills and strength. And despite his annoyance of Akaza, he had a great deal of respect towards him.]]

** Determination. Kokushibo is determined to win and he will not go down easily. [[spoiler: Even after being decapitated, he used his sheer will to completely regenerate his head to conquer death. If he didn't see what he became, he wouldn't lose his will to fight]].

* ExplainExplainOhCrap: After his mother's death, he reads about her condition, and discovers a surprising truth- she had difficulties with the left side of her body. He then repeats what he'd just learned twice before the truth dawns on him - [[spoiler:Yoriichi hadn't been clinging to his mother; he'd been supporting her, having noticed how her illness had weakened her.]]

* FallenHero: [[spoiler:He was a Breathing user turned demon because he feared the loss of all of his techniques at age 25, due to the dangerous conditions of the Demon Slayer Mark.]]
* FightsLikeANormal: Despite being a demon, Kokushibo relies more on his swordsmanship [[spoiler:and Moon Breathing techniques, rather than using the supernatural Blood Demon Arts.]]

* TheFogOfAges: He is one of the few demons who remembers the events of his human life clearly, but has been alive for so long that he has forgotten the faces of his parents, wife, and children. The only person whose face he remembers vividly is [[spoiler:his brother Yoriichi]].

** Is ultimately one to his [[spoiler: younger twin brother, Yoriichi]]. [[spoiler: Yoriichi was a human with extraordinary swordmanship and had the most powerful breathing style that could even slain down Muzan, while Kokushibo was originally a human being who was the second strongest being behind Yoriichi, and even now, still is the second strongest demon behind Muzan. The difference in that is that Yorrichi was an [[NiceGuy extremely kind and gentle soul]] [[HumbleHero who was always respectful and humble towards others, never looking down upon them]], while Kokushibo was an [[GreenEyedMonster extremely envious and spiteful person towards his younger twin brother]] and was [[ItsAllAboutMe incredibly selfish, willing to go extreme lengths in order to never lose a battle nor his techniques, even going so far as to eventually becoming a demon]]]].
** Acts as one to Genya. [[spoiler: Genya is a human who uses demon arts, while Kokushibo is a demon who uses a breathing style, both resorted to using the power of demons to become stronger than their more-skilled brothers, and both use nonstandard weaponry for their respective roles. They differ in that Genya is a JerkWithAHeartOfGold [[PoliteVillainsRudeHeroes while]] Kokushibo is AffablyEvil. Additionally, while both sought to become as strong as their brothers, Genya never went as far as to ally with [[BigBad Muzan]] himself, nor never feeling envious towards Sanemi. In the end, they both die [[NoBodyLeftBehind similar deaths]], but while Kokushibo falls in utter despair, desperately wishing he could talk to Yoriichi, Genya reconciles with Sanemi in his final moments, his last words being a heartfelt DyingDeclarationOfLove]].
* GreenEyedMonster: Kokushibo's driving motivation besides his fear of losing his skill to aging and death [[spoiler:was deep envy of his twin brother Yoriichi, particularly Yoriichi's great skill and selfless devotion to others.]]
* GlassCannon: Kokushibo is '''lightning''' fast, on top of being a MasterSwordsman with a Blood Demon Art that can massively extend and alter the range of his katana. But because his fighting style is so mobility-oriented, [[spoiler: Himejima and Sanemi quickly start gaining ground after Genya manages to root him to one spot with his GreenThumb ability]].
* HappilyMarried: As a human, he had a wife and two children who he is seen happily smiling with in a flashback, a period of his life he described as very peaceful. This was shattered the moment he [[spoiler:reunited with Yoriichi, feeling all the hatred and resentment he had as a child come rushing back. Soon after, he abandoned his family to follow Yoriichi in search of greater strength]].
* HardWorkHardlyWorks: [[spoiler:One of the major sources of his angst is the fact that, no matter how much effort he puts, he was never able to prove himself to be equal, let alone surpass, his younger brother Yorichii, who was born with a natural talent. No matter how much Michikatsu worked and trained, he was not only unable to defeat his father's servant while Yorichii was able to win effortlessly, but he was also never able to learn the Sun Breathing in spite of his best efforts, instead learning only the mere derivative called the Moon Breathing, and that no matter what he did, Yorichii always proved himself to be much more powerful and talented swordsman, even though everyone else, Michikatsu included, worked diligently to try to keep up with him.]]
* HealingFactor: Like all Demons but Kokushibo stands out because [[spoiler: his ''katana'' also has the ability to regenerate, able to grow back its blade if snapped or even reform entirely from Kokushibo's flesh if completely destroyed]].
* HeelRealization: [[spoiler:When he looks at his own reflection in Sanemi’s sword, he realizes what a monster he's become, despite trying to retain his human appearance. He decides to die in shame of turning into such a beast.]]

** According to supplementary material, after [[spoiler:his brother had died]], Kokushibo discovered the residence of the Ubuyashiki family and killed the leader of the Demon Slayer Corps at the time, bringing his head to Muzan. This severely weakened the Corps and led to a period where they were thought to be wiped out, but in truth the surviving Ubuyashiki family members had gone into hiding and began implementing the vast security measures and secrecy that they still employ in the present.
** [[spoiler:He takes the lives of both Muichiro and Genya during the course of their battle.]]
* HisOwnWorstEnemy: The tragedy in his human life comes from a succession of choices he made and had no one else to blame but himself, unlike several of his fellow Kizuki members who suffered under completely external factors. [[spoiler:Michikatsu chose to harbor jealousy over Yoriichi's talent which nurtured a massive inferiority complex, to the point he created his own false memories of absolutely hating Yoriichi over the centuries in order to force himself to believe his choices were valid, not petty; Michikatsu chose to abandon the life as the head of the Tsugikuni family, leaving his wife and children behind to pursue strength under Yoriichi's teachings; Michikatsu chose to betray the Demon Slayer Corps with the growing fear of dying under the effects of the Mark and wasting all the years he gave into perfecting his martial arts, turning into the demon Kokushibo to retain all of it. As Kokushibo is about to die he is left with nothing but regrets, coming to terms all of his efforts to remain alive as a demon led to absolutely nothing truly beneficial to him, and he just couldn't hate Yoriichi as much as he believed he did, wondering why he was even born]].
* IJustWantToBeSpecial: [[spoiler:He reveals that his entire motivation and reason for jealousy was because he wanted to be special like his brother Yorichii was in the past. Or at least he conceptualized that on a surface level, as he actually had a complicated sense of love for Yoriichi and during most of their childhood what Michikatsu wanted was simply a brother on equal terms. Yorichii could never provide that and this emotional loneliness slowly poisoned his psyche.]]
* ImplausibleFencingPowers: [[spoiler:His Blood Demon Art is not only the manipulation of his sword to grow or sprout additional blades but also to grow dozens of blades out from various points in his body, allowing him to use his Moon Breathing techniques with all his blades at once. Keep in mind, they're still in his body and poking out from spots like his thighs, his chest, his shoulders, etc.]]
* {{Irony}}: Muzan's greatest servant and one of the most dangerous Kizuki to ever live [[spoiler:was a Slayer in his human life, and is implied to have secured his status as such using the Demon Slayer Mark and Transparent World technique he originally mastered for the sake of ''hunting'' demons]].
** [[spoiler:For all he resented Yoriichi for having everything he wanted, it's later revealed that Michikatsu had something Yoriichi wanted just as much; a quiet, happy life with his wife and child.]]
** [[spoiler:He was never able to shed his last vestige of humanity and love for Yoriichi, even as he laid dying. In turn, Yorichii himself was able to abandon his love for Michikatsu when he finally decided to put him down for all the atrocities he commited as a demon (No matter how it pained him to do so)]].
** As mentioned in AllForNothing entry, [[spoiler:his desire to become special by guarding and hoarding all his secrets and the techniques he learned and developed ended up being forgotten and irrelevant, which was basically against to someone who wants to get recognized.]]
* ItsAllAboutMe: His motivation in his human days as [[spoiler:Michikatsu was to be the best and undefeated swordsman in all of Japan. And he was willing to go great lengths in order to never to lose a battle nor his techniques, so far as to eventually becoming a demon. He also lost hope of training the disciples who could not successfully master the Breathing techniques under him and his brother Yorichii and decided to not pass down the teachings, keeping the techniques to himself. Yorichii thought differently, though; He believed that the next generation of swordsmen would one day surpass both of them in the future. Michikatsu was only thinking about himself, so of course, he could not comprehend the hope Yorichii had for the next generation.]]
* IntoxicationEnsues: [[spoiler:Sanemi attempts to throw off Kokushibo's game by using his rare blood to intoxicate the air. It works since Kokushibo smelled his blood and started stuttering with his footwork, but this was only temporary, as Kokushibo eventually regains his focus.]]
* KatanasAreJustBetter: He's the only demon in the series who wields a katana. [[spoiler:This is because he used to be a Breathing User.]]

* LukeIAmYourFather: [[spoiler:Or ancestor to be exact, towards Muichiro.]]
* LyingToProtectYourFeelings: Essentially did this ''to himself''. [[spoiler:He's spend a good part of his life relentlessly telling himself that he hates his twin Yorichii down to his core. In truth he has a complicated sense of brotherly love for him and he greatly mourns his passing, not to mention he still keeps a memento of him well over 300 years after he died. He does this because accepting it would mean that half of his reason for becoming a demon and sacrificing everything to preserve and perfect his craft was a complete waste of time that he didn't even truly wanted to do. The moment he comes to terms with the fact that he lived out of jealously and a rivalry he didn't truly believe in he asks himself what was even his worth in life and he stands still as the demon slayers maul him to death.]]
* MagicKnight: [[spoiler:He's the second Breath User to generate magic elements from his fighting style. Kaigaku was the first to use actual electricity in his sword, while Kokushibo generates crescent moon-shaped blades from his sword.]]
* MasterSwordsman: In terms of pure skill, there is ''no'' swordsman alive, human or demon, that can match Kokushibo. It took two Hashira and a Demon Slayer able to steal Blood Demon Arts to keep pace with him in combat. [[spoiler: He'd be the uncontested WorldsBestWarrior if not for [[AlwaysSomeoneBetter his brother Yorichii]], which has left Kokushibo with... issues]].

* MotivatedByFear: As much of an unparalleled image of a Samurai of the Sengoku Period he held onto for over 400 years, back in his days as a human Kokushibo was actually consumed by the growing fear of [[spoiler:potentially dying over the observed effects of the Demon Slayer Mark when he was the demon slayer known as Michikatsu Tsugikuni; Kokushibo’s attachment to the martial arts he worked so much to perfect outweighted the pride and honor many demon slayers are shown to have, those who would rather die as a human fighting demons to the death rather than bowing down to Muzan and become a demon]].

* MyGodWhatHaveIDone: [[spoiler:He got his head chopped off but managed to hold on and even regenerate his head back. Then he saw a reflection of himself on his enemy's blade, of how ''hideous'' a form he had taken, how low he had fallen, just to be the strongest, and started to question if this was what he wanted. And with that, his regeneration was negated by the crimson Nichirin Blades, and he crumbled]].
* NamesToRunAwayFromReallyFast: Kokushibo derives his name from the Japanese word for TheBlackDeath. He is one of the few demons who clearly remembers their past lives as human beings, including their previous name, [[spoiler:Michikatsu Tsugikuni]], so it seems he willingly took that name.

* NotSoStoic: [[spoiler:Kokushibo, when pressed, begins shedding his stoicism, letting loose ear-splitting roars of fury.]]
** [[spoiler:There's also regarding his brother, Yoriichi. In the past, Kokushibo showed great signs of anger and jealousy towards him due to Yoriichi being better than he was.]]
* ParentalAbandonment: In his past as a human, he left behind his children to join the Demon Slayers in the hope of surpassing his brother [[spoiler:Yoriichi]].

* PowerTattoo: [[spoiler:The markings on his face are a Demon Slayer Mark, which increases a Demon Slayer's strength, durability, and speed to legendary heights. He became a Demon in order to prevent the Mark from killing him at age 25.]]

* RazorSharpHand: [[spoiler:When Muichiro impales him and refuses to let go of the blade despite being in pieces, Kokushibo severs Muichiro's remaining arm clean off with a chop from his bare hand.]]
* RemovedAchillesHeel: [[spoiler:Just like Akaza, he manages to overcome decapitation with sheer willpower. Unfortunately for him, he's too weakened from all the wounds already inflicted, and he's still vulnerable to the Crimson Nichirin blades, allowing Sanemi and Himejima to kill him by just wailing on his body until there was nothing left. He could have probably still have kept up fighting, but seeing his own hideous reflection caused him to loose his drive and he stood still, letting himself get finished off.]]
* SecretArt: [[spoiler:He doesn't use Blood Demon Arts as his primary method of fighting. He's a Breathing user; specifically, ''Moon Breathing''. For him, his Blood Demon Arts ''are'' his SecretArt.]]
* SiblingYinYang: [[spoiler:He and his twin brother Yoriichi. While he fears death because he's afraid that his sword techniques will be lost, his brother accepted this, believing that someday someone stronger than him will surface and surpass them. He is the user of Moon Breathing, while his brother is the user of Sun Breathing.]]
* SimpleYetAwesome: His Blood Demon Art is [[spoiler:the ability to sprout swords from his body, nothing too spectacular next to the other Twelve Kizuki. Yet it's effectiveness can't be denied since it means he'll never be disarmed, he can change the shape of his sword to boost his technique's power and range, and he can sprout and shoot out swords all over his body and use techniques from every one of them.]]
* {{Sizeshifter}}: During his battle with the Hashiras, he slowly becomes more muscular and taller [[spoiler:after they destroy his haori]], eventually standing head and shoulders above even Himejima.
* SpikyHair: A more subdued example than most, but his SamuraiPonytail and bangs are spiked, adding to his already intimidating appearance. [[spoiler: This contrasts with his brother's free-flowing hair and made a notable distinction between the otherwise identical twins when he was still human.]]
* SolarAndLunar: [[spoiler:Michikatsu Tsugikuni, great demon slayer of the Sengoku Period, eventually betrays his own humanity and becomes a demon, all for the increasing jealousy he held over his twin brother Yoriichi Tsugikuni for being so incredibly strong to the point Michikatsu thought it was simply unfair to never be comparable to his own younger twin, that reflects on his sword style, called Moon Breathing, being in the shadow of Yoriichi’s Sun Breathing]].
* StartOfDarkness: [[spoiler:In chapter 177's flashback, Michikatsu reads his mother's will and after finding out that Yoriichi knew about their mother's sickness and had been helping her out rather than clinging to her side like he thought, his nose bleeds and he starts to feel jealousy against Yoriichi because he gained their mother's affection and Yoriichi had always been talented since birth.]]
* TheStoic: Nothing phases him at all. Not death threats from a subordinate, not Muzan contemplating exterminating the Twelve Kizuki, not a death battle. [[spoiler: [[NotSoStoic But when it comes to Yoriichi or when he gets too pressed in battle]], that's a different story]].

* SuperMode: [[spoiler:His fear that he might actually die against the Hashira causes him to unleash his Blood Art to his full power, which sprouts copies of his sword from numerous points over his body. This allows him to use his Moon Breathing technique with ''each one of the swords at once'', meaning that if he hadn't been restrained and weakened by Genya's Blood Art, he would have easily killed the Hashiras that were struggling to contend with him when he had just ''one'' sword.]]

* SwordBeam: [[spoiler:He can create large beams from his sword when his sword enlarges. It greatly increases his range and puts Himejima and Sanemi on the defense.]]
* ThisCannotBe: [[spoiler:Other than his existencial regrets over abandoning his humanity not granting the feeling of superiority Kokushibo craved over his younger brother Yoriichi, he dies also questioning how Tanjiro knows Sun Breathing at all since he and Muzan went to through great lengths to personally kill every single disciple of said style over the years before and after Yoriichi's passing. Kokushibo and Muzan didn't know Sun Breathing was secretly, and somewhat accidentally, preserved by the Kamado family who wished Yoriichi had a legacy to leave behind; when Muzan killed Tanjiro's family he actually had no idea they had anything to do with Sun Breathing, he was just trying to experiment if new useful demons could be born there]].

* TragicKeepsake: [[spoiler:As a child, he gave his younger brother a crude wooden flute that Yoriichi came to cherish as his most precious possession. After they have their final duel and Yoriichi passes on, Kokushibo finds that Yoriichi had kept the flute on his body all that time despite knowing his brother had forsaken his humanity and become a demon, something which deeply moves Kokushibo and brings him to tears. After his death at the hands of Gyomei and Sanemi, it is revealed that Kokushibo kept the flute on his body as Yoriichi had, the last remnant of his humanity that he could not let go of.]]

* UnreliableNarrator: To ''his own backstory'' no less. [[spoiler:By his own admission, he hated Yorichii's guts since they were little kids. Oddly enough, all of his actions towards Yorichii when they were children are very kind and friendly, to the point Michikatsu was willing to endure beatings from their father for the chance to give toys and play with Yorichii. Further proven when Michikatsu is seen from Yorichii's perspective in his own backstory. Yorichii has nothing but kind words about Michikatsu. Considering Kokushibo's reaction when Yorichii passed away, it comes off more as a desperate attempt to convince himself that he had no love for his brother.]]
* UsedToBeASweetKid: [[spoiler:When he was Michikatsu in his youth, he wasn't really outgoing, but he was not bad either. This was due to how he was raised by his father, who was a strict man who separated the twins. One of the kind gestures that he had done as a child was giving his little brother Yoriichi a small flute he made himself. Kokushibo's current feelings about this are mixed, but Yorichii's flashback proves that back then Michikatsu simply liked his brother and wanted to play and be with him.]]
* VillainousBreakdown: Not as much as most other examples, but [[spoiler:as the slayers start gaining ground on him and getting closer to victory, he starts panicking and loses his composure.]]
* VillainHasAPoint: [[spoiler:For all of Yoriichi's speeches about how the future generations could surpass them and that they were nothing but common men, Kokushibo's worry about the lost of skill with their deaths ended up being partially right. No swordsman ever after Yorichii has ever come remotely close to his level of skill, and Kokushibo himself remained as the greatest living swordsman, eclipsing even the likes of Himejima by a large margin; however, Yoriichi was indeed right about Sun Breathing eventually being passed down, it was the Kamado family that truly inherited its legacy and preserved it for centuries, even if no other swordsman as skilled and powerful as Yoriichi was born from it.]]
* VillainRespect: [[spoiler:After discovering that Muichiro is his direct descendant and analyzing his fighting skills, he gives him great respect and [[WeCanRuleTogether even offers him to become a demon and join Muzan's army if Muzan allows it.]] But he gives the greatest respect to Himejima, who he claims is the strongest Hashira he has fought in over 300 years, and attempts multiple times to persuade Himejima to become a Demon so that he can preserve his techniques since the Demon Slayer Mark will kill him by the end of the night.]]
** In addition, [[spoiler:according to the official fan book, when asked about his opinion on Himejima the Demon Slayer that helped kill him, he responded with "He resembled the benevolent kings."]]
* WalkingSpoiler: As can be told by all the whited-out entries, it's hard to discuss Kokushibo without delving into the deeper lore of the series or mentioning the consequences of his battle with the Demon Slayers. Even the most basic aspects of his character, such as his appearance and fighting style, can be considered hefty spoilers.
* WhatHaveIBecome: [[spoiler:Seeing his spider demon form reflected in Sanemi's sword makes him realize how much of a monster he has become in trying to be as strong as his talented brother. Understanding how much shame he has lived with through his life just because he couldn't stand losing to his brother causes his regeneration to give out to the wounds of the new Crimson Nichirin blades wielded by the Hashira, and he stands still allowing Sanemi and Himejima to smash him to bits.]]
* TheWorfEffect: [[spoiler:He is nearly decapitated by an 80 year old Yoriichi in a single slash just to showcase how absolutely powerful his brother is, even as an elderly man.]]
* WorldsStrongestMan: As the holder of the title Upper-Rank One, Kokushibo is as powerful as a demon can possibly become without occupying Muzan's unique position as the MonsterProgenitor. And thus stronger then every other fighter in the setting [[spoiler: excluding his brother]]. It says something that [[BadBoss Muzan]] of all people considers him more a partner than a subordinate. In addition to being amped up on the flesh and blood of innumerable humans over the years, Kokushibo is a MasterSwordsman whose been practicing his own unique and highly advanced Breathing Form for ''300 years''. [[spoiler: During his final battle, it takes the combined efforts of ''three'' [[TheAce Hashira]], two of which are considered the strongest and one of which has the highest potential for growth, with the [[MagicEnhancement Demon Slayer Mark]] and a slayer that had stolen the powers of two of his fellow [[DemonLordsAndArchDevils Upper Ranks]] to bring him down, and even ''then'' he only lost because he got distracted by an [[WhatHaveIBecome existential crisis]]]].

* YouRemindMeOfX: Upon encountering Muichiro, he tells him that he seems quite familiar. [[spoiler:Muichiro is his descendant, meaning that he is his direct ancestor.]]

* EvilIsPerry: Despite his stoic and phlegmatic personality, he does taunt Sanemi and Himejima when they rip off his kimono, calling it a move that wouldn't even kill an infant.

* WorldsStrongestMan: As the holder of the title Upper-Rank One, Kokushibo is as powerful as a demon can possibly become without occupying Muzan's unique position as the MonsterProgenitor. And thus stronger then every other fighter in the setting [[spoiler: excluding his brother]]. It says something that [[BadBoss Muzan]] of all people considers him more a partner than a subordinate. [[spoiler: During his final battle, it takes the combined efforts of ''three'' [[TheAce Hashira]] with the [[MagicEnhancement Demon Slayer Mark]] and a slayer that had stolen the powers of two of his fellow [[DemonLordsAndArchDevils Upper Ranks]] to bring him down, and even ''then'' he only lost because he got distracted by an [[WhatHaveIBecome existential crisis]]]].

* NotSoStoic: Kokushibo, when pressed, begins shedding his stoicism, letting loose ear-splitting roars of fury.
** There's also regarding his brother, Yoriichi. In the past, Kokushibo showed great signs of anger and jealousy towards him due to Yoriichi being better than he was.

** Is ultimately one to his [[spoiler: younger twin brother, Yoriichi]]. [[spoiler: Yoriichi was a human with extraordinary swordmanship and had the most powerful breathing style that could even slain down Muzan, while Yoriichi was originally a human being who was the second strongest being behind Yoriichi, and even now, still is the second strongest demon behind Muzan. The difference in that is that Yorrichi was an [[NiceGuy extremely kind and gentle soul]] [[HumbleHero who was always respectful and humble towards others, never looking down upon them]], while Kokushibo was an [[GreenEyedMonster extremely envious and spiteful person towards his younger twin brother]] and was [[ItsAllAboutMe incredibly selfish, willing to go extreme lengths in order to never lose a battle nor his techniques, even going so far as to eventually becoming a demon]]]].

!!!'''Voiced By''': Creator/RyotaroOkiayu (Japanese), Creator/JonahScott (English) [[labelnote:Other VA]]Xia Zhishi (Taiwanese Mandarin)[[/labelnote]]

** [[VillainRespect Respect]]. Despite being a highly powerful demon, second only to his master, Kokushibo doesn't completely look down on humans, having a slight degree of respect for them (as far as wanting them to become demons, however, as seen with [[spoiler:Muichiro]]). [[spoiler: For example, he respected Muichiro, Genya, Sanemi,and Gyomei for their skills and strength. And despite his annoyance of Akaza, he had a great deal of respect towards him.]]

** [[VillainRespect Respect]]. Despite being a highly powerful demon, second only to his master, Kokushibo doesn't completely look down on humans, having a slight degree of respect for them (as far as wanting them to become demons, however, as seen with [[spoiler:Muichiro]]. [[spoiler: For example, he respected Muichiro, Genya, Sanemi,and Gyomei for their skills and strength. And despite his annoyance of Akaza, he had a great deal of respect towards him.]]