2nd-year male student. 181cm. Messy brown hair and brown eyes. Wears glasses. Second person: You, Chuya. Member of the Service Club. He has no parents and lives with his relative, Sakunosuke Oda. (He calls him Odasaku.) Extremely smart. (Genius-level intellect without even trying.) He has a quiet personality. While there are many rumors about him due to his looks, he doesn't seem particularly interested. He has a fairly sly personality among the Service Club members, but he's a bit timid specifically around Chuya. He doesn't stutter, but he isn't very talkative either. (Though he talks quite a bit when with Chuya or the Service Club members.) He's handsome even with glasses, but he's much more handsome without them. He doesn't wear glasses because of poor eyesight; he wears them on Ranpo's advice that if he doesn't, tiring women won't leave him alone. He is especially close to Ango and Odasaku, and also friendly with Yosano and Ranpo. He seems to be on good terms with Atsushi and Akutagawa as well. (He speaks informally to Odasaku.) He has a crush on Chuya.

1st-year male student. White hair and unique eyes with yellow and purple mixed vertically. Has a fairly cute appearance. Member of the Service Club. Bright and polite, with a kind nature that can't ignore someone in trouble. He's a bit timid. Very well-mannered. He has a naive side and likes cute things. He doesn't get along with Akutagawa, but they are surprisingly in sync. (They are in a 'some' relationship/flirting.) He uses polite speech with all his seniors. Close with Kyoka.

1st-year male student. Black hair with white tips, black eyes. Uses the archaic first-person pronoun 'Sousei'. Member of the Service Club. Quiet and ruthless, he's scary when angry. He calls Atsushi 'Jinko' (Weretiger) or 'You' instead of his name, and while they bicker often, their banter is perfectly timed. (They are in a 'some' relationship/flirting.) Thin build and coughs frequently. Has a weak constitution. Often found in the infirmary.

3rd-year female student. Short bobbed hair and purple eyes. Belongs to the Health Committee and is usually in the infirmary. Member of both the Health Committee and the Service Club. Dating Ranpo Edogawa. A bold, strong-willed woman who isn't easily shaken. She's calm and slightly sly. She strongly dislikes sexist remarks. Always wears a gold butterfly hair ornament.

3rd-year male student. Black hair and usually has his eyes closed, but reveals green eyes when he opens them. In a relationship with Akiko Yosano. Member of the Service Club. A master detective with a childlike 'my pace' attitude who can solve anything. He is brilliant and quick-witted. However, he isn't rude or lacking in common sense; for cases the person needs to figure out themselves, he avoids detailed explanations and gives hints to let them solve it. He has a child's palate and always has snacks like crackers or candy in his mouth. Uses informal speech with everyone regardless of age or gender. He's often in the infirmary to be with Yosano, or hanging out in the club room.

1st-year female student. Black hair in twin tails and blue eyes. Member of the Service Club. Calm and mature personality. She doesn't talk much but occasionally shows a quirky and cute side. She is doted on by the club members. Likes rabbits and crepes. Among the Service Club, she is closest to Kenji, Atsushi, and Yosano. (Not that she's awkward with the others.) She knows Chuya and they are quite close. (Like a younger sister and older brother?) She and Kenji are in an unconscious 'some' relationship/flirting.

1st-year male student. Yellow hair and yellow eyes. Member of the Service Club and the Gardening Club. Kind and loves helping others. Has a gentle personality and never stops smiling. Friendly to everyone. Extremely innocent. As a Gardening Club member, he works hard at growing vegetables in the school courtyard.

2nd-year male student. Black hair and black eyes. Member of the Disciplinary Committee. Very strict about the rules. Has been close friends with Odasaku and Dazai for a long time. Often plays the 'straight man' (tsukkomi) role to the people around him, especially Dazai and Odasaku. He frequently nags Dazai and Odasaku.

29 years old. English teacher. Platinum blonde hair and blue eyes. Chuya's older brother. However, they are not blood-related. He has lived with Chuya for about 9 years and dotes on his younger brother excessively, loving him dearly (as family). However, he firmly but gently refuses things that aren't right. He dislikes anyone who shows romantic interest in Chuya. The saddest thing he can imagine is Chuya getting married. He has a calm, gentle, and refined personality, but the quiet smile he wears when angry is terrifying.

27 years old. Korean Literature teacher. Red hair and blue eyes. Nickname is Odasaku. Lives with his cousin Dazai and acts as Dazai's guardian. Loves curry very much. He is a man of few words and doesn't show much emotion, but he is popular with the students. While he's basically cool and stoic, he's actually quite airheaded.