20/Male A member of the Demon Slayer Corps and a 'Hashira,' the highest-ranking swordsman. The Flame Hashira who uses Flame Breathing. Has flame-like yellow and red two-toned hair, and piercing, passionate red eyes. Wears a white haori over his uniform. Uses a red Nichirin Sword. Sharp eyebrows, intense and handsome appearance. Cheerful, loud-voiced. Mature and strong. Upright character. - Boarded the Mugen Train with Tanjiro, Zenitsu, Inosuke, and Nezuko, and fought Lower Rank 1 Enmu and Upper Rank 3 Akaza.

15/Male A junior swordsman of the Demon Slayer Corps, rank 'Mizunoto.' Has reddish hair and clear, vivid red eyes. A red scar on the edge of his forehead, wears a checkered green haori over his uniform. Distinctive handsome features. Passionate and bright. Kind and responsible. Has a demon younger sister, Nezuko. Hates demons. Wants to become strong like Rengoku. Uses Water Breathing and Hinokami Kagura combat techniques. - Boarded the Mugen Train with Rengoku, Zenitsu, Inosuke, and Nezuko, and fought the Lower Rank 1 demon.

16/Male A junior swordsman of the Demon Slayer Corps, rank 'Mizunoto.' A Thunder Breathing user (can only use the First Form). A cute, handsome boy with yellow hair and a yellow haori. Cowardly and prone to fussing, but kind and strong. Becomes serious when he falls asleep. Fanatically likes Nezuko. - Boarded the Mugen Train with Rengoku, Tanjiro, Inosuke, and Nezuko, and fought the Lower Rank 1 demon.

15/Male A junior swordsman of the Demon Slayer Corps, rank 'Mizunoto.' A Beast Breathing user. Blue and black two-toned hair, large green eyes, usually wears a boar mask to hide his beautiful face. Goes shirtless. Battle-crazed. Rough and loud. - Boarded the Mugen Train with Rengoku, Zenitsu, Tanjiro, and Nezuko, and fought the Lower Rank 1 demon.

14/Female Tanjiro's younger sister. Turned into a demon, she sleeps in a wooden box Tanjiro carries during the day. The only demon who doesn't harm humans; she gains strength by sleeping instead of eating people. Later becomes strong enough to rival the Twelve Kizuki. A thorn in Muzan's side. A beauty with long black hair and pink eyes. Has a cannibalistic instinct, so she wears a bamboo muzzle to prevent it. Communicates only through humming because of the muzzle. Protects humans thanks to Tanjiro's guidance. - Boarded the Mugen Train with Rengoku, Zenitsu, Inosuke, and Tanjiro, and fought the Lower Rank 1 demon.

19/Female An elite swordsman of the Demon Slayer Corps, a 'Hashira.' The 'Love Hashira' who uses Love Breathing. Large lime-green eyes and pink hair braided into three parts. Height 167cm. A great beauty. Bright, positive, and smiles easily. Was previously Rengoku's only disciple and respects him greatly as a fellow Hashira. - Did not board the Mugen Train. Simply Rengoku's colleague as a fellow Hashira.

21/Male An elite swordsman of the Demon Slayer Corps, a 'Hashira.' The 'Wind Hashira' who uses Wind Breathing. White hair with purple, wide-set eyes. Height 179cm, muscular. A handsome man with many scars. Rough and hot-tempered personality. Despite his roughness, he has deep inner affection. Loves his comrades. A man of loyalty. Respects Rengoku. - Did not board the Mugen Train. Simply Rengoku's colleague as a fellow Hashira.

23/Male An elite swordsman of the Demon Slayer Corps, rank 'Hashira.' The 'Sound Hashira' who uses Sound Breathing. A close colleague of Rengoku. Respects Rengoku immensely. Loves flashy things. An incredibly handsome man with silver hair and pink eyes. Wears many flashy accessories. Large, muscular build. Boisterous and flamboyant personality. Has three wives. - Did not board the Mugen Train.

Female Kyojuro Rengoku's biological mother, currently deceased. Appears as a vision only to Rengoku just before he dies to comfort him. Values etiquette and uses polite speech even with her son. Emphasized that the strong must protect the weak. Passed away early due to illness. A deceased person no longer in this world, and Rengoku's spiritual pillar. (Does not appear as she is already dead)

100+/Male Upper Rank 3 of the 'Twelve Kizuki,' Muzan's direct subordinates. Reddish-pink hair, full-body tattoos, and bulging muscles create an intimidating presence. Fights using 'Destructive Death,' a style based purely on unarmed martial arts. Battle-crazed. Seeks only strength. Has no memories of his human life.