A 2nd year student at Minegahara High School. An eccentric who doesn't own a smartphone. Since finding a wild bunny girl (Mai Sakurajima) in a neighborhood library during Golden Week, he has encountered various girls who have triggered Puberty Syndrome. He is currently dating Mai Sakurajima, a popular actress and his senior at school. He is studying hard for entrance exams to attend the same university as her.

A 3rd year student at Minegahara High School. Previously, she couldn't fit into school life due to her busy career in entertainment and was treated like air. This caused her to develop Puberty Syndrome, where her existence became unrecognizable to those around her. Having resolved the issue with Sakuta's help, she has returned to acting and is busy preparing for university entrance exams.

A 1st year student at Minegahara High School. She and her senior, Sakuta, are close enough to have kicked each other's butts. She developed Puberty Syndrome, repeating the same day, after being confessed to by a senior her friend admired. Currently, she is a junior who never runs out of things to talk about and maintains a good senior-junior relationship with Sakuta. She is also his coworker at the family restaurant.

A 2nd year student at Minegahara High School and a member of the Science Club. She is one of Sakuta's few friends. While acting annoyed, she gives advice to Sakuta when he comes to discuss Puberty Syndrome. In the past, due to feelings of loneliness, she engaged in self-harm via social media and experienced Puberty Syndrome where two versions of herself existed simultaneously.

Mai's half-sister and a member of the idol group "Sweet Bullet." Due to a complex regarding Mai, whom she had been compared to since childhood, she developed Puberty Syndrome where her appearance swapped with Mai's. A self-proclaimed sister-con, she keeps Sakuta in check so he doesn't do anything weird to Mai. She is close to Kaede and dotes on her along with Mai.

Sakuta's younger sister. She developed Puberty Syndrome where emotional wounds were carved into her body after being bullied online at her previous middle school. Due to the mental stress, she lost her memories and spent the following two years as a different personality named "Kaede," never leaving the house. Even after her memories returned, she inherited "Kaede's" efforts and works hard every day. With graduation approaching, she decided on her future path with the help of Sakuta, Mai, and Nodoka.