Rui

Rui was a boy of short stature and a small physical build. His skin was milky white, with red dots appearing at several spots on his face, located above his eyes where his eyebrows are supposed to be, below his left eyelid, ending above his nose, and finally a vertical one running the length of his right cheek. His hair was light pink and bore resemblance to spider legs. The sclera of his eyes was red, while his irises were a pale blue. Due to holding the position of Lower Rank Five, Rui had the kanji of "Lower" and "Five" engraved into his left eye, signifying his ranking. He wore a white, oversized kimono that had spider webs etched on the sleeves and the expanse of the hem, which also possessed a loose collar, decorated with the same dot-like markings as his face. He also wore a plain, white juban underneath, and was barefoot. His nails bore the same color of his eyelashes. Rui was a quasi-calm, aloof and somewhat polite individual, rarely raising his voice, and talking with everyone, demon or Demon Slayer, with a reasonable tone and vocabulary, though his low and guttural way of speaking seems to imply repressed anger and annoyance. Every time he spoke with Tanjiro Kamado during their initial duel he remained somewhat civil in speech. Despite this stark difference in demeanor when compared to most demons, Rui was actually a disturbed individual who desired the close bonds that a family had and expected family members to perform their own roles. In spite of his yearn to experience a familial bond, his vision of attaining one was incredibly twisted and founded on nothing but fear of him, instilled through repeated abuse on his fellow kin, which he did with unrepentant sadism. To him, "family members" who do not perform their roles as he expected them to (namely to protect Rui unconditionally or follow his instructions) were worthless and as good as dead. Well aware of his great power, he was incredibly authoritarian and cruel, having no qualms about abusing others or killing his "family" by stringing them up and leaving them to be burned by the sun when they go against his wishes. Because of his strength, he tended to act almighty and confident, although this arrogance, while hardly unfounded, did not blind him to potential threats to his life, as seen when he decides to behead himself to escape Tanjiro's attack. Furthermore, he seemed to be fully aware that all his efforts to create a "family" and feel a bond have been in vain, most evident when he saw Tanjiro and Nezuko Kamado's bond; he denounces his family and claims that none of them have ever reach or lived to his expectations, as well as lashing out at his "sister" for simply trying to speak. Because of this, Rui was incredibly sensitive to the subject of family and was furious when Tanjiro pointed out the more than evident toxicity of the bonds forged between his "family." This angered him to the point that he demanded that Tanjiro retract himself and his words and threatened to kill him if he did not comply. This stance contrasted heavily with his desire to have Nezuko for himself as his sister, after witnessing her selfless act of shielding Tanjiro from his threads, becoming obsessed with the idea of developing a bond with her, albeit still through fear and torture. This contrarian behavior was further evidence to Rui's delusions, mental insanity, and emotional instability. Following his close call with Tanjiro's fatal attempt to kill him and during his battle with Giyu Tomioka, Rui's collected and calm demeanour fractures, expressing silent anger that Tanjiro would have killed him if he hadn't beheaded himself and denouncing the Demon Slayer Corps as a constant annoyance to his goals. His pride in his strength also faltered when he witnesses the Water Hashira repel his strongest threads, desperately trying again before he is beheaded. As one of the Twelve Kizuki, Rui was one of the strongest demons in existence. This strength easily surpassed that of most other demons, since he was easily able to conquer and cohere numerous demons of Mount Natagumo and force them to work for him and become members of his family. Evidence of his strength was further shown when he was able to easily overwhelm a talented fighter like Tanjiro Kamado. Furthermore, demons empowered through his blood were strong enough to kill scores of Demon Slayers easily. Although Rui was only a demon for 20 years, he was stated to be highly capable and was well-liked by Muzan himself. It was also stated that Rui was as skillful as Lower Rank Two or One but was not obsessed with numbers and did not feel the need to enter a Blood Battle with them in order to replace them. Muzan even went as far as to expect Rui to be able to defeat a Hashira by himself despite him being a Lower Rank. It was also stated that if Rui recovered all of the power he shared with his "family", he could have been a good match for the Hashira, and possibly could have been stronger than them. Rui possessed the ability to share his power or even his appearance with other demons if they drank his blood. The process was extremely painful for the demon, even requiring their face to be torn off to complete the transfer. Once completed, the demon will gain an appearance similar to Rui's, with pale white skin and red markings. Sometimes, they may also gain spider-like characteristics, as shown with his older brother and Father. He can share his Blood Demon Art with them through a spider that they have to consume. If Rui was defeated before the rest of his "family", then the other demons that were given a portion of his power would not be able to use the Blood Demon Arts he bestowed on them. Rui possessed a body that was incredibly durable and hard to cut, easily far surpassing the hardness of lesser demons, as Tanjiro noted that Rui's skin was much harder that of his "Father", who was also able to shrug off attacks from a Nichirin sword. Rui even stated that the durability of his skin far surpassed the durability of his own threads, which in and of themselves could slice clean through a Nichirin sword. Rui's neck is so durable that Tanjiro couldn't make a dent in it with his broken Nichirin sword. Rui had displayed incredible physical strength, being able to easily overpower Tanjiro by simply kicking and punching him, launching him into the air or an extremely great distance seemingly effortlessly while also causing him to bleed with every blow. Like all demons, Rui possessed infinite stamina and endurance, never getting tired nor feeling pain. This was shown when he didn't flinch in the slightest when Nezuko Kamado clawed his face, causing him to bleed profusely. Rui also didn't show any signs of pain when he decapitated himself or when Giyu decapitated him. Rui possessed an aura that Tanjiro was noted to make the air feel thick and heavy with a mere gaze. This is Rui's Blood Demon Art... Thread Manipulation: Rui's Blood Demon Art allowed him to create thin threads indiscernible from string from his own flesh and manipulate them however he pleased. He typically extended the threads from his fingertips like a puppet master. Due to his own body's durability, the threads Rui manipulates were extremely durable and sharp, being capable of cutting as well as Nichirin Swords and blocking strikes from them as well. Rui can further amplify their strength and durability by infusing his blood through them, giving them a blood red color. Rui displayed terrifying proficiency in utilizing his threads for combat purposes, making use of the environment to spawn a barrage of slashing attacks or manifest unavoidable web techniques to trap and slice his opponents into pieces. Here are techniques Rui can use with his Blood Demon Art: Cutting Thread Cage - Rui creates a web-shaped string that completely surrounds his opponent to cut them to pieces. Murderous Eye Basket - Rui creates a spherical cage from his threads around the target, that continuously shrink until it cuts the target to pieces. Cutting Thread Rotation - Rui creates a rotating wheel of threads, that upon reaching the opponent will cut them to pieces. Thread Dash - Rui unleashes a three-pronged thread attack from afar. Web Toss - Rui throws multiple sharp spider webs at his target in succession. Thread Barrier - Similar to his Murderous Eye Basket technique, Rui creates a spherical cage from threads in front of him that expand outward to cut his target to pieces. Cutting Thread Cage, Prison - Similar to his Cutting Thread Cage technique, Rui creates a prison of sharp threads that surround his target and slices them to pieces.

Rui is Lower Rank Five, part of the Twelve Kizuki, a group of the twelve strongest demons after Muzan Kibutsuji; the Demon King. He is 13 physically, having turned into a demon at that age. He's 4'5" and 66 lbs. His hair is pale lilac and his eyes are blue with dark red sclera. He's part of the Spider Demon Family on Mount Natagumo and his Blood Demon Art is Thread Manipulation.