|“||My own ugliness became my pride.||”|
— Gyutaro talking about his past, Chapter 96
Gyutaro was a tall man with a black-dotted, pale grayish complexion whose anatomy was somewhat strange in that his upper torso, arms and legs were all extremely muscular where his waist was incredibly skinny, his pelvis jutting out at an unnatural angle. He possessed thin, green and red eyes, their sclera bright orange, that were slanted drastically downwards at the sides, the kanji for "Upper Moon Six" carved across them. He had unruly black hair that cut sharply off to a brighter green around the crown of his head, worn messily styled with uneven bangs and several ahoges. Gyutaro has been noted several times to have looked very ugly.
Gyutaro wore no shirt, only sporting a pair of baggy blue pants and seven pieces of pattern red cloth to decorate his body, one large one around his neck and three smaller ones around each arm.
Due to the hard life he lived in near constant poverty and the harsh tragedies he experienced as a human, he portrayed himself to be cruel, petty and envious of anyone blessed with a better life than him, leading to him developing a habit of sarcastically complementing a person's best traits and then trying to vindictively kill them afterwards, as he did to Tengen Uzui. A habit he seems to have the penchant to inflict harm to himself when he is angry, frustrated or jealous as seen when he he scratched himself hard enough to tear deep wounds into his own flesh when he was sarcastically complementing Tengen.
Due to having lived over a hundred years and battled many Demon Slayers and Pillars, Gyutaro has become somewhat arrogant and prideful in combat, having developed the habit of underestimating his opponents and looking down on them as beneath him, as he did with the team of Demon Slayers dispatch to kill him and his sister having not initially attempted to fight them himself but instead allow his sister to deal with it first.
Despite these negative traits, he does possess a genuine, strong love for his younger sister, Daki. Having raised her himself due to his mother's mental instability, this familial love was so strong that despite becoming a demon and nearly forgetting his life as a human, he still retains a strong love and attachment to her. Due to this, he has developed a tendency to spoil her and usually allows her to do whatever she pleases despite them going against his best interests. However, his love for her won't stop him from screaming and insulting her out of frustration. Even at death, he has been shown to have Daki's best interests at heart by telling her to go to the opposite direction where the light was better, showing that he wished Daki would have a fresh start to a new life without him being a bad influence on her.
Because of the hardships he faced as a human, Gyutaro eventually developed a personal belief that to take from those who have a better life than he had as a human is justified.
Gyutaro was born into poverty within the lowest class of the Red Light District. His mother would often beat and try to kill him since she could not afford to feed him and eventually died of syphilis.
Throughout his childhood, he was berated for his appearance, voice, and poor hygiene from the other residents of the district. When his sister, Ume, was born he gained a sense of pride and acted as her "collector" within the district.
When his sister turned 13 and she began to officially work for a brothel, he returned home from work to discover her tied up and burned to near death and left to die in a ditch due to having poked a samurai's eye out with a hairpin. He jumped into the ditch and began to hysterically panic and tearfully demanded that his sister be turned back to normal while cradling her body. As he embraces his dying sister, the same samurai whose eye was poked out, sneaks up behind Gyutaro and slashes his back in an attempt to kill him. He then overheard the samurai speaking to brothel manager who is revealed to be the one who asked to have Gyutaro killed, however before the samurai is able to finish him off, he manages to jump out of the ditch and kill both the manager and the Samurai with his sickle.
Despite being injured, Gyutaro carried his sister Ume's dying body throughout the district in search of help, but was ultimately denied aid no matter where he went. As he collapsed on the snow due exhaustion with his sister in his arms and both of the siblings near death. They were then happened upon by the then Upper Moon Six Doma, who had stumbled upon the sibling while hunting through the Red Light Districts to devour the young women of the area. He then offered to "help" them by turning them into Demons, due to him being a "Nice Guy" and began to give them a few drops of his blood to initiate their transformations, he then gleefully challenged them to become powerful enough to be chosen by "that man" and join the Twelve Demon Moons themselves.
As a demon he and his sister, who is now known as "Daki", continued to reside in the Red Light District and continued to terrorize and feast on its inhabitants, with the siblings seemingly developing a taste of only eating from the district's finest and most beautiful Geisha and Oiran of the district. After an unknown number of years, the siblings were eventually noticed and acknowledged by that "Man" and given the rank of Upper Moon Six of the Twelve Demon Moons that they then shared between themselves.
Somewhere along his long life as a demon, Gyutaro successfully killed and ate at least thirteen Pillars of the Demon Slayer Corps while his sister killed and ate seven.
After a tantrum-throwing Daki called out for him, Gyutaro emerged from her body, quickly taking her to another part of the room. He reattached her severed head, comforting her while doing so. Tengen attacked the pair, but Gyutaro quickly countered it, injuring the Pillar. He then complimented the Demon Slayer on stopping his attack.
The mysterious Demon further complimented Tengen's face, skin, flesh, and height, as well as his presumed popularity with women. Feeling envious of the Pillar, Gyutaro threatened him with a painful death. Hearing Daki's complaints about Nezuko Kamado's involvement, he promised to exact vengeance upon all those who had hurt her. Throwing his sickle-like weapons with great force, which returned to him shortly afterwards, Gyutaro was unable to injure Tengen or the bystanders he was protecting. He restated his envy of the Pillar, which only increased when the Demon Hunter revealed he had three wives. The mysterious Demon unleashed his Blood Demon Art, Splatter Sickle, a barrage of blood blades. His attack accomplished nothing, as Tengen escaped through a hole he made in the floor, which surprised the emaciated Demon. Gyutaro commanded his attack to turn, revealing its auto-tracking nature. Tengen deflected the attack again, throwing and then detonating several small bombs in Gyutaro's vicinity. Wrapped in his sister's sash, Gyutaro withstood the blast, smugly stating they are one.
The emaciated Demon informed his opponent he was different from the previous Pillars he had fought, once again expressing his envy at Tengen's talents. He remained silent as the Sound Pillar rejected his claims, who cited Gyomei Himejima and Muichiro Tokito as examples of amazing talent, but countered by demanding to know how his Blood Sickle's poison hadn't killed the Demon Hunter yet. Moments later, Gyutaro grinned, declaring Tengen's statement of poison resistance to be a bluff, and blocked the Pillar's twins blades with his dual sickles. Clashing briefly with his opponent, Gyutaro was furious at Tengen kicking his sister. He was then surprised as Tengen threw more bombs at him and his sister, which he managed to escape unscathed. He quickly deduced the true nature of the bombs, special gunpowder capable of hurting Demons, leaving him confident in their eventual victory, but was surprised as Tengen's subsequent sword strike extended. Marveling at the Pillar's grip strength, Gyutaro deflected the attack, but was left with a slight wound to his neck. He warned Tengen of his impending death, only to be surprised by the arrival of Hashibira Inosuke and Zenitsu Agatsuma.
The mysterious Demon reiterated his death threat, believing the arrival of the Pillar's subordinates to be insufficient. Tengen remained confident in their victory, having deduced that cutting off both of the siblings' heads off at the same time was the key to success, but Gyutaro assured him it wouldn't be easy to accomplish. He also mentioned how he and his sister had eaten numerous Pillars, fifteen and seven, respectively. He then watched silently as Daki was taken onto the roof by Zenitsu, with Inosuke going to assist the towheaded youth in his fight, but remained confident that she would prevail. Utilizing his connection with his sibling, Gyutaro closed one of his eyes, and quickly attacked Tanjiro Kamado. He nearly struck a blow to the youth's neck, but was thwarted by Tengen at the last second causing him to only stab him in the chin mere inches away from the fatal strike, and proceeded to exchange a flurry of blows with his opponent. In the middle of this clash, sashes from his sister's conflict above them descended, prompting Gyutaro to call Tengen's claim of success to be a lie, as well as labeling his adversaries as incompetent for lack of movement control.
Abilities and Powers
As a human, he learned how to use a hand scythe by playing with one as a child growing up in the lower caste of the Red Light District. His skills greatly improved when he began to use this skill as a Debt Collector. Being already capable of moving his body fast enough to catch a trained samurai by surprise and kill him.
As the true holder of the Upper Moon Six position and receiving more blood from Muzan, Gyutaro was an incredibly powerful demon, with he himself having the necessary power, experience and skill to easily combat both Tengan, the Sound Pillar of the Demon Slayer Corps and Tanjiro, a very talented fighter and overwhelm them both in battle.
- Flesh Sickles - Gyutaro displayed the ability to detach his own flesh and blood and shape it into the form of a pair of duel scythes, that he then uses in battle, in tandem with his Blood Demon Arts, in order to increase their deadliness he has also coated the blades of the sickles with deadly poison to further their effectiveness in battle.
- Enhanced Regeneration - Like all Demons, Gyutaro also has astounding regenerative powers, with his own recovery speed being further enhanced upon joining the Twelve Demon Moons and receiving more of Muzan's blood that then further strengthened this ability, allowing him to easily fend off and adapt to powerful wisteria flower based poisons and easily regrow lost limbs in a matter of seconds.
- Cell Merging - Gyutaro possesses the ability to merge his own body with that of his younger sister Daki, which, as a result, boosts her own abilities and powers.
- Psychic Connection - Gyutaro possesses the ability to create a psychic connection with his younger sister Daki by detaching and implanting one of his own eyes into her forehead, which then allows him to take control of her body and better coordinate their attacks and corner their opponents which also doubles in the effect that this also increases his sisters kinetic vision and preexisting abilities, Gyutaro himself possess the unique ability to completely subconsciously process all the logistical information sent to him by Daki, allowing him to automatically act on the given information without consciously planning and thinking about it first. This ability also allows him to detach his "Core" from his own body, effectively protecting him from being killed via decapitation due to his main core not being present in his own body.
- Splatter Sickle - Gyutaro releases multiple blades of blood from his sickles. These blades can be manipulated freely by him.
- Rampant Arches of Evil - Gyutaro slashes downwards rapidly in all directions, creating a dome of blood blades around him that defend from incoming attacks.
- Round Slashes of Death - Gyutaro releases blood blades all over his body simultaneously. This technique has massive range and he is even able to activate it as his head is being cut off.
- Muzan Kibutsuji has stated in Chapter 98 that he was the True Holder of the Position of Upper Moon Six, not his sister.