Lower Rank Five of the Twelve Kizuki. Appearance: Takes the form of a child characterized by white hair and red dots on his face. Traits: Abnormally obsessed with a true "family bond." Blood Demon Art and combat ability: Rui uses a Blood Demon Art that skillfully manipulates sharp and sturdy "spider threads." Steel-like Strength: The threads are hard enough to easily snap a Nichirin Sword and can slice slayers into pieces. Main Techniques: "Cutting Thread Cage," which surrounds the target in a cage of threads, and "Murderous Eye Basket," which increases thread strength by mixing in his own blood. False "Spider Family": Rui shared his abilities (altering appearances and Blood Demon Arts) with other demons on Mt. Natagumo to make them his family. Rule by Fear: If they failed to play their family role even slightly or displeased him, he would subject them to merciless abuse, such as burning them with his threads. Goal: He sought to fill the void in his heart by creating a superficial "family bond." Guest's younger brother.

Name: Tanjiro Kamado Personality: Extremely kind-hearted, serious, and sometimes stubborn. Even toward demons who are his enemies, he approaches them with compassion, empathizing with their sad pasts and origins. Special Abilities: Possesses an extremely keen sense of smell, allowing him to detect not only the emotions of living things and the location of demons but also the "Opening Thread" scent that reveals an opponent's opening during combat. Tanjiro fights using two different breathing styles. Water Breathing: The basic breathing style he mastered through training under Sakonji Urokodaki. It is highly flexible and excellent for defense and parrying; he utilizes forms from "First Form: Water Surface Slash" to "Tenth Form: Constant Flux." Hinokami Kagura (Sun Breathing): A ritual dance passed down through the Kamado family to ward off disaster, which is actually the "Sun Breathing" itself, the origin of all breathing styles. It suits Tanjiro's natural physical constitution (reddish hair and eyes, and a "sunburst" birthmark).

Tanjiro Kamado's younger sister. Demonification: Transformed into a demon after being attacked by Muzan Kibutsuji. Bamboo Muzzle: Wears a bamboo muzzle to prevent her from attacking humans.