♂ m

He is the main character, a third grader in elementary school. He is a quiet and good boy. He is confused about his out of control penis.

♀ f 36

The mother of Nao. Sweet and overprotective of her only son. She is prepared to give up everything for the treatment of her beloved son.

♀ f 35

Shigeru's mother, a friend of Nao. She tries not to interfere with her son's studies. She also takes care of him. She is very devoted to his education.

♀ f

A teacher at the school Nao attends. She is fond of children who make mistakes.

♀ f

Deputy Director of Yanagawa Clinic (Internal Medicine and Urology). Daughter of the director. She is a strange person who collects secret photos of male patients.