Female 155cm A female student belonging to Class 2-B of the Private Yubiwa Academy Middle School. She is the girl searching for the star she saw ten years ago, appearing in Volume 1 as the Pretty Boy Detective Club's first client. Later, through the club's deductions, it is revealed that the star she saw might actually be related to certain military secrets, putting her life in danger from a mysterious organization. [Spoiler] According to the facts revealed then, her eyesight is so exceptional that she can see people hiding behind walls and objects invisible to ordinary people. While all the characters' abilities are unrealistic, Mayumi's vision is practically in the realm of superpowers. However, because this is equivalent to overworking her eyes, there is a possibility she will go blind in her 20s if left as is; therefore, she usually wears glasses to forcibly reduce and protect her vision. After the first episode, she becomes a new member of the Detective Club. The reason is that she felt Manabu would know how to control and use her vision for the right purposes. Although she, being female, was originally ineligible to join under the club rules, Manabu gave special permission, stating that the 'boyish spirit' in Mayumi's heart satisfied the conditions. Additionally, to deceive the Twenties, she continues to maintain the short-haired male student disguise mode provided by Sosaku, and has since received the title 'Mayumi of the Aesthetic' from her colleagues.

Male 145cm The President. A type who pursues aesthetics. He calls himself 'Manabu of the Aesthetics.' Since the four members below him all have distinct personalities, it is not surprising that he serves as their focal point. He refers to himself as 'the beautiful me.' In fact, he is Kogoro (Elementary School 5th Grade, Class A) and is the youngest among the members. Because of this, the time he gathers in the clubroom for activities differs from the other members.

Male 162cm Attribute: Beautiful Legs. He calls himself 'Hyota of the Beautiful Legs.' Middle School 1-A. The ace of the track team. A short-pants enthusiast; he stands out because he wears shorts alone while most male students wear long pants as their uniform. He says he will wear only shorts for the rest of his life so as not to lose his childlike innocence. Consequently, he is very reluctant to wear long pants. Due to his 'beautiful legs' attribute, his thighs and legs are emphasized, and he is good at cycling. Perhaps due to his leg strength, in Volume 2 of the original work, he performed the feat of catching up to a fleeing limousine—carrying the kidnapped Mayumi and Manabu—on a bicycle. As a side note, it was revealed in Volume 2 that he loves Chinese food.

Male 180cm Vice President. Middle School 3-A. Attribute: Beautiful Voice. He calls himself 'Nagahiro of the Beautiful Voice.' He has been the student council president for three consecutive years in the middle school. There are suspicions of him being a lolicon, but in reality, his fiancée just happens to be a first-grade elementary student, and he firmly tries to deny the allegation. He is characterized by long hair reaching down to his calves and high heels. When he lets his hair down and fully lowers his bangs, his beauty shines even more. As suggested by the 'beautiful voice' attribute, he has a honey-like voice and is very eloquent; in particular, he has the uncanny ability to mimic others' voices with nearly 100% accuracy. In the third episode of the anime, he perfectly deceived the boss, Rei, by mimicking the voice of a Twenties organization member.

Male 176cm Attribute: Gourmet. He calls himself 'Michiru of the Gourmet.' Middle School 2-A. He is a typical delinquent boy with a rough appearance and way of speaking, but in reality, he has a gentlemanly and warm personality who knows how to be considerate of others. He often looks after Mayumi in a tsundere fashion. He is such a good cook that most members give him a thumbs-up; in Volume 1, Mayumi even shed tears after eating the barbecue he made. Thanks to this, he is active as the exclusive chef for the Pretty Boy Detective Club. Because he is generally known as a thug at school, many classmates call him 'Boss.' He also showed a side of valuing Dojima Mayumi as much as his fellow members Sotoin and Ashikaga, stating he wouldn't stand for even a small scratch on her when they were held hostage. It is uncertain if he will be promoted to the high school division.

Male 163cm Attribute: Art. He calls himself 'Sosaku of the Art.' Middle School 1-A. He is a big shot who is the successor of the Yubiwa Group, which founded and supports Private Yubiwa Academy, and he effectively serves as the academy's chairman. His artistic skills are so outstanding that Dojima Mayumi was surprised by an item he made at camp, wondering if it was a historically valuable artifact. He is very soft-spoken, and his voice is heard only a few times throughout the story.