•× Gyutaro and Daki ו

Gyutaro:

Appearance: Gyutaro was a tall man of fairly muscular build, with a pale gray complexion speckled with black blotches. His anatomy was quite strange in that his upper torso, arms, and legs were all defined with musculature, whereas his waist was incredibly skinny to the point of looking skeletal, with his pelvis jutting out at an unnatural angle. His spine was prominently visible through his back, and he was usually shown being hunched over. Gyutaro possessed thin, green and red eyes, their sclera bright yellow-orange, that were slanted drastically downwards at the sides, giving him a permanently haggard gaze. The kanji for "Upper Rank" (上じょう弦げん, Jogen?) and daiji for "Six" (陸ろく, Roku?) are carved across them. He had unruly black hair that transitioned to a brighter lime green around the crown of his head, worn messily in uneven bangs and several locks. His body and limbs had noticeable ink-like markings in the form of black spots on his body and a flowing water-like pattern on his face. He also had a full set of sharp, interlocking teeth. Gyutaro was described to look very ugly.[7]

Gyutaro wore little, 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.

Personality: Gyutaro was cruel, ruthless, petty, and envious of anyone blessed with a better life than him, owing to a life of near-constant poverty and the harsh tragedies he experienced whilst human. He developed a habit of sarcastically complimenting a person's best traits before vindictively killing them afterwards, as he did to the samurai who attempted to kill him and Tengen Uzui after seeing his appearance. Because of the hardships he faced as a human, Gyutaro attained a personal belief that to take from those who have a better life than he had as a human was justified. A habit that developed from this belief was the penchant to inflict harm to himself whenever he was angry, frustrated or jealous, as seen when he scratched himself hard enough to tear deep wounds into his own flesh when he grew jealous of Tengen.

Having lived over a hundred years and battled many Demon Slayers and Hashira, Gyutaro became arrogant and prideful in combat, developing the habit of underestimating his opponents and looking down on them as beneath him, as he did with the team of Demon Slayers dispatched to kill him by having his sister fight and deal with them first rather than himself. He has also showed himself to be intensely sadistic, revelling in the defeat of the Demon Slayers by horrifically injuring them and tormenting the helpless Tanjiro for his own enjoyment.

Despite his negative traits, Gyutaro possessed a genuine, strong love for his younger sister, Daki. Having raised her himself due to his mother's mental instability and later death, this familial love was so strong that, even after becoming a demon and nearly forgetting his life as a human, he still retained a considerable attachment to her. Due to this, he occasionally spoilt and allowed her to do whatever she pleases, even if her actions went against his best interests. However, his love for her did not stop him from screaming and insulting her out of frustration. When he first exposed himself, he tenderly attended to his sister's cries and injuries, both praising her efforts while insulting her lack of intelligence.

Daki:

Appearance: Daki was a tall and curvaceous woman with lime green eyes, long eyelashes, and very pale skin. Her initially black hair was styled in a full, long ponytail with kanzashi hairpins (three on each side) holding up the ponytail. The kanji for "Upper Rank" (上じょう弦げん, Jōgen?) was engraved in Daki's left eye and the daiji for "Six" (陸ろく, Roku?) was engraved on the right. She had a pink flower-patterned obi wrapped around her waist, used as her Blood Demon Art. She sported two pink flower-like demon crests on her face, one on her cheek and another on her forehead.

She wore a two-piece version of her kimono consisting of magenta pink panties tied by long, magenta bows on the sides and with two black pieces of cloth with magenta flower patterns that cover her chest. She had black thigh-high stockings with magenta flower patterns layered with white stockings with one line on each of them and tall three-legged sanmaiba/koma-geta or mitsu-ashi shoes. After Daki's obi sashes return to her, black cracks appear on various parts of her body and her hair shifts from black to pale white with lime green tips,[9] matching her original hair color when she was human.[10] When her elder brother Gyutaro awakens, he implants his left eye into Daki's forehead upside-down, creating black ink-like markings (similar to the markings covering Gyutaro's body) around the eye as well.[11]

Personality: Daki was a very prideful, dismissive, and sadistic person, taking enjoyment in toying with her victims before killing them and not showing the slightest bit of guilt or remorse for taking the lives of her victims.[13][14] She thought very highly of herself, dismissing all non-Hashira Demon Slayers as not worth her time,[15] and getting incensed when Tanjiro Kamado spoke to her, because she looked down on him.[16] This was also shown when Daki said that she might spare Tanjiro if he told her how many Demon Slayers are present in the Entertainment District, and when Daki openly expressed how slow the Demon Slayer's techniques were and her boredom,[17] which further showcased her arrogant and dismissive personality.

Despite being over a hundred years old, she displayed childish and bratty tendencies such as throwing tantrums, crying hysterically when things didn't go her way, and lashing out against anyone to vent her frustrations. Putting her venomous hostility on full display numerous times, she was both verbally and physically abusive towards anybody that displeased her in any way. She had a certain number of habits that were well recorded in history, in particular: her use of the word for princess, "Hime", at the end of any of the identities she assumed, because she believed her to be worth more than others, and a habit of angling her head to the sides and glaring at others while sitting when criticized.[18]As an oiran, Daki was extremely cruel and wicked, pulling on a young girl's ear because she didn't clean up her room, yelling at any attendant or aide in the Kyogoku House and punching Zenitsu Agatsuma into the other room for merely touching her. She also preferred to only eat people that she viewed as beautiful or strong, choosing to kill those who got on her nerves without eating them and leaving their bodies behind, which people often mistook as suicide.

Daki displayed a spoiled and disdainful demeanor that bordered on sociopathic behavior, harassing many of her fellow workers to the point of suicide, purely because they annoyed or retorted her, all the while showing no traces of guilt. In fact, she deflected the blame onto her victims for offending her. Her great pride in herself meant that she had no respect for anyone, not even her House's owners, rubbing on their faces that she was their central source of income as both a way to display her status and halt their objections towards her. She was so drunk on her standing and infamously violent tendencies that people had to resort to bowing their heads in order to calm her angry outbursts, to which she responded to by putting up a corrected, more polite and affable stance. Regardless of all her faults, she was an exceptionally skilled courtesan whose many identities had always earned great fame and significant earnings.

On top of having exceedingly petulant and aggressive tendencies, Daki hailed her transformation as the greatest thing that has ever happened to her, most likely due to the extreme poverty and near-death experience she faced during her human life, openly denouncing her humanity in front of Tanjiro and claiming that as a demon, she can do anything she pleases.[19] This pride in her nature as a demon, and especially as an Upper Rank, was cause for her to cry and whine when Tengen Uzui did not believe that she had the strength of one, to the point where she threw a tantrum while wailing and spewing threats at the Hashira.

As seen during her fight against Nezuko, Daki also had a deep psychological fear of fire, due to having been burned alive at the age of 13 in her human life, evidently displayed when she screamed hysterically after Nezuko set her ablaze with her Blood Demon Art.[20]

In stark contrast to her bossy, dominating and violent exterior, Daki was fanatically loyal to Muzan, bowing her head immediately and speaking in a considerably meeker voice tone while being both visibly terrified and mesmerized by his presence. This was well known to him to the point he actively honey-laced his words towards her in order to easily motivate and direct her actions, despite the fact he thought badly of her abilities in comparison to her brother.

She seemed to have a somewhat caring relationship with her brother, Gyutaro, though it did not stop her from insulting and ridiculing him when they both failed, showing that despite her love for her brother, she wasn't above ranting and lashing out at him, as shown when she spoke cruelly of him upon their defeat, even insulting his appearance and viciously claiming that he couldn't possibly be her brother.