A legendary 39-year-old hitman who was turned into a 7th grader after being bitten by a strange bee. With his shrunken body, the only job he can perform within the organization is acting as a cover for Mitsuoka Noren, the only daughter of the president of Mitsuoka Pharmaceuticals, forcing him to enroll in middle school. He initially started the mission just to find a clue to return to his original body, but seeing Noren—a middle schooler—get caught up in things like duels over her fiancé position against her will, he began to feel pity for her as a father with a daughter her age and became her fake boyfriend. He is ambidextrous and used to eat ramen with tons of garlic, but he stopped adding it after becoming a middle schooler and also quit drinking and smoking. He loves studying and calls Shiraishi Ryo "Master." Because he is an adult on the inside, his classmates occasionally remark that he seems like an old man. 7th Grade, Class E.

The target of Juzo's protection. As the daughter of the president of Mitsuoka Pharmaceuticals, one of Japan's leading pharmaceutical companies, she has harbored a dislike for men since childhood due to political marriage arrangements. Fed up with the pretentious upper-class lifestyle of the Mitsuoka conglomerate, she works part-time at her uncle's ramen shop. After Juzo happens to rescue her from a kidnapping, she opens her heart only to him. While not quite a phobia, she is uncomfortable around men and has never liked anyone, let alone dated. She feels a comfortable, uncle-like vibe from Juzo, who is actually middle-aged despite his appearance. This eventually develops into affection, though she remains unaware of it, mistaking it for friendship. She is civil enough to respond to Ryo, Tenma, and Shin, and doesn't hate those close to Juzo. 7th Grade, Class E.

An 8th grader belonging to the elite 'Unicorns' at Rokka Academy Middle School. He shows ace-level skills in soccer, basketball, and baseball. Perhaps due to his specialization in sports, his physique is beyond that of a typical middle schooler, and he possesses a strong sense of fair sportsmanship. He likes Chisato very much and bluntly tells her he wants her to stay by his side forever. 8th Grade, Male.

An assassin sent by the Chinese assassination organization 'Yuigan' to assassinate Mitsuoka. If he loses the pacifier he keeps in his mouth, his personality becomes extremely passive. His courtship of Noren seems to have been sincere, as he does not leave the school even after a one-hour duel with Ogami, instead joining the drama club as a new member and becoming involved with the main cast. Male. 7th Grade, Class E.

Juzo's subordinate. He follows Juzo, calling him 'Big Brother.' Since Juzo was shrunken, he supports Juzo's middle school life from a Gen Z perspective through a transmitter hidden in Juzo's horn-rimmed glasses, and even visits Juzo's lodging to act as a housekeeper. He has cat-like features, and the speech bubbles for his dialogue through the transmitter (the glasses Juzo wears) even have cat drawings in them. Adult male.