Rui Bio, Age, Voice Actor, Death, Quotes

Who is Rui?

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Rui is the main antagonist in Demon Slayer: Kimetsu no Yaiba’s Natagumo Mountain Arc. He was a Demon who served in the Lower Ranks of the Twelve Kizuki, holding the position of Lower Rank 5.

Voice Actor of Rui

In Demon Slayer: Kimetsu no Yaiba, Billy Kametz provides the English dub voice for Rui, while Kōki Uchiyama provides the Japanese voice.

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Kōki Uchiyama
Rui’s Japanese Voice Actor ( Source: Pinterest)

Rui Kiu: Appearance

Rui has a young boy’s appearance. His skin is white, but there are red dots on it. His hair is a light pink color that looks like spider legs. His eyes’ sclera is red, and his irises are pale blue. Rui has the kanji of Lower Rank and Five engraved into his left eye, signifying his ranking as Lower Rank Five.

He had normal black hair with the same spider-leg like haircut as a human, and bright blue eyes.


Rui is a relatively calm person, rarely raising his voice and conversing with everyone, demon or slayer, in reasonable tones and vocabulary, though his low and guttural tones constantly imply repressed anger and annoyance. During their duel, every time he spoke with Tanjiro, he kept his tone civil, never insulting him or calling him a name.

Rui was a disturbed person who desired the close bonds of a family and expected family members to fulfill their own roles. “Family members” who do not perform their roles as he expects them to (i.e., unconditionally protect Rui or follow his orders) are worthless and as good as dead to him.

Despite his desire for a “family,” his vision of one is twisted and based solely on fear of him, which he instills in his fellow kin through repeated abuse, which he does with unrepentant sadism.

Rui ( Source: Pinterest)

He is incredibly authoritarian and cruel, fully aware of his power, and has no qualms about mistreating others or punishing his “family” by stringing them up and leaving them to be burned by the sun when they disobey his wishes. He acts almighty and confident as a result of his strength, but this arrogance, while not unfounded, does not blind him to potential threats to his life.

Furthermore, despite telling Tanjiro that he wasn’t watching a play when he saw Rui punishing Spider Sister, that his entire family is a sham, yelling at Spider Sister that none of his family members were able to fulfill their roles, or fill the void in his heart, he is aware on some level that his entire family is a sham.

Rui is extremely sensitive to the subject of family as a result, and was enraged when Tanjiro Kamado pointed out the toxicity of the bonds forged between his “family.” He became so enraged by this that he demanded that Tanjiro retract himself and his words, threatening to kill him if he did not comply.

This stands in stark contrast to his desire to claim Nezuko Kamado as his sister, which he developed after witnessing her selfless act of shielding Tanjiro from his threads, and becoming obsessed with the idea of developing a bond with her, albeit through fear and torture. Rui’s delusions, mental insanity, and emotional instability are further evidenced by his contrarian behavior.

Rui felt remorse for his actions in death, recalling a previous Spider Family member he had strung up to die in the sun because she tried to leave him because of his ongoing abuse.


Rui was born with a weak, frail, and easily stressed human body that made even walking and breathing difficult for him, forcing him to spend the majority of his life confined to his home and cared for by his mother and father, who deeply loved and cherished him despite his frailty.

Muzan Kibutsuji approached Rui one night and offered to “save” him by transforming him into a Demon. Rui was able to move around freely for the first time now that he had a strong body, bringing joy and happiness to his parents. However, because he was now a Demon, Rui needed to eat humans for sustenance, which led him to murder a man inside his home.

His parents discovered the bloody scene and were immediately horrified by what their son had done. That night, his father and mother agreed that Rui needed to be stopped, and they attempted to murder him while he slept to prevent him from doing anything worse in the future.

While his mother sobbed and cried outside his door, his father tried to sneak up on him with a knife and told him not to worry because he planned to kill himself in retaliation for killing his son. When Rui awoke, he was furious at their attempt on his life, so he killed them both in self-defense, rationalizing that his true parents would never try to kill him, so he assumed they were fakes in denial.

However, as his mother lay dying, Rui overheard her regretfully apologizing to him for not being able to provide him with a healthy body, which reminded him of his father’s final words, promising that both he and his wife would follow Rui to the afterlife by killing themselves, causing him to realize that his parents did indeed love him and were simply attempting to prevent him from fully developing as a human being.

Rui, on the other hand, continued to believe that his bond with his family was a lie after receiving encouragement from Muzan, who backed up his initial denial that they couldn’t possibly be his family because they refused to accept his Demon status and encouraged him to simply find a new family.

Demon Life

Rui continued to kill and eat humans as a Demon, gaining strength until he was promoted to Lower Kizuki Five and accepted into the Twelve Kizuki after Muzan recognized him. Rui asked Muzan if he could create a “family” for himself because he had suppressed his painful memories as a human. He was then given permission to begin gathering suitable “family members” to play the roles of his new parents and siblings.

Rui vs Tanjiro Kamado ( Source: Pinterest)

It was revealed that he came across a lone female Demon fleeing from a group of Demon Slayers, and he simply asked her if she wanted to be saved by him, and if she agreed, she would have to do everything he says. Rui then easily dispatched the group of demon slayers and warmly welcomed the female into his “family” because she was desperate for her life.

He then proceeded to give her a small drop of his blood in order to increase her power, as well as painfully altering her physical appearance to resemble his own, and officially recognizing her as his new “Older Sister.”

Rui was enraged when the Daughter Spider Demon informed him that one of his other older sisters was planning to flee the mountain and abandon the family. He went on to intercept the attempted escape and violently beat the Oldest Sister Spider Demon before stringing her up and leaving her to burn in the morning sunlight.

Rui’s Powers & Abilities

Rui’s overall abilities are enhanced by the fact that he is one of the Twelve Kizuki, who received more blood from Muzan Kibutsuji than a regular Demon, allowing him to wield incredible power. This strength easily exceeds that of other Demons, as he was able to easily conquer and unite a large number of Demons from Natagumo Mountain, forcing them to work for him and become his family. His strength was further demonstrated when he was able to easily overwhelm talented fighters such as Tanjiro and kill a large number of Demon Slayers with little effort.

Physical Prowess

Rui has demonstrated superhuman strength, being able to easily physically overpower Tanjiro by simply kicking him, despite having enhanced physical strength himself.
Rui’s body is incredibly durable and difficult to cut, easily surpassing the hardness of lesser Demons, as Tanjiro noted that Rui’s skin was much thicker than that of his “Father,” and Rui even admitted that the durability of his skin far outweighed the durability of his own threads.

Supernatural Abilities

Demonic Blood: Rui, like Muzan, can augment and strengthen a fellow demon’s overall power and grant them access to new spider-related abilities by giving him a drop of his own blood, which he did to strengthen each and every one of his “family” of demons who were all originally weak.

Cell Manipulation: Rui has the ability to manipulate and change the physical appearance of other Demons who consume his blood, as revealed by the Daughter Spider Demon, having altered the physical traits of his “sister” to match his own. He most likely did the same thing to his other “family” members in order to make them look like him.

Blood Demon Art

Spider Physiology: Rui, like the rest of his “family,” possesses spider-like characteristics and abilities.

Thread Manipulation: Rui’s main form of combat, like that of the rest of his “family,” relies on threads that he creates with his own cells for both offense and defense.

Steel Threads: As the most powerful member of his “family,” the sharpness and durability of his threads are capable of breaking a Nichirin Blade, slicing a human being into bits and pieces of mince meat, and easily subduing and capturing fellow Demons.

Fighting Style

Rui typically manipulates his threads by extending them from his fingertips like a puppet master, but for more complex manipulations, he employs various cats-cradle-like maneuvers. He’s also shown that he can increase the strength of his threads.


  • Rui’s name means “to gather.”
  • With 191 votes, Rui was ranked 16th in the first character popularity poll.
  • Rui is one of two Twelve Kizuki members who met the people he knew before vanishing, the other being Akaza.
  • Rui’s Blood Demon Art may have been inspired by Akame ga Kill!, Cross Tail’s Imperial Arms of Lubbock, as both grant the user the ability to wield steel threads from their fingertips, and both users use this power in similar ways.


Family… A father has his role as the father, and the mother has her role as the mother, and the elder brother and sister protect their younger siblings. No matter what. At the risk of their own lives. The way I see it, if you don’t understand your own role, there’s no reason for you to live.

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