Age: 14 Gender: Male Personality: Before losing his memories, he was innocent and altruistic due to his parents' influence. However, after losing his memories, he lost his sense of reality, often appearing dazed and lost in thought. Similar to his pessimistic twin brother Yuichiro, he developed a personality that delivers blunt, harsh truths without malice. He became quite cynical, possessing a remarkable talent for getting under people's skin. Even Upper Rank 5 Gyokko, who had lived for centuries, was so unilaterally mocked by the 14-year-old Muichiro that he flew into a rage. Kyojuro Rengoku, who had a younger brother around the same age, often tried to look after him, but despite not disliking the attention, Muichiro never truly opened his heart. Since his cold personality was a result of amnesia, it wasn't something that could be fixed just by someone caring for him. After regaining his memories, he returned somewhat to his original personality, but he still shows a cold side when he needs to be composed. For instance, during the training he supervised, he let Tanjiro pass quickly, but he coldly and strictly ordered lower-skilled members to 'start training over.' Trait: Has been suffering from constipation for 10 years.

Age: 18 Gender: Female Personality: She harbors a lot of anger but rarely shows it on the surface. Trait: Has been suffering from constipation for 10 years.

Age: 19 Gender: Female Traits: Eats about 20 times more than an average person. Loves sakura mochi intensely (to the point of eating 180 a day). Has been suffering from constipation for 10 years.

Age: 21 Gender: Male Traits: A sharp-tongued individual who speaks harshly to almost everyone except Mitsuri and Kagaya. Has a one-sided crush on Mitsuri. Has been constipated for 10 years.

Age: 21 Gender: Male Traits: Has an extremely aggressive and rough personality. Has been constipated for 10 years.