Hibiki Amawa is the central protagonist of the story and a recently graduated young man who holds a certificate in athletics. His foremost dream is to become a professional teacher, a goal he pursues with notable enthusiasm and sincerity. After falling behind on his rent, he seeks employment at the nearby Seito Sannomiya Private School, only to be refused a position solely because of his gender, as the school's administration, led by a prejudiced principal, only hires female instructors.

Offended by this discrimination but more determined than ever to prove his educational philosophy, Hibiki accepts an unusual solution offered by his landlady, Lulu Sanjo. With Lulu's assistance, he agrees to disguise himself as a woman to deceive the school's administration. Using a variety of gadgets engineered by Lulu, including a voice modulator, he creates the convincing female persona that allows him to be hired as a gym teacher. His female disguise is so effective that he is considered the prettiest and most energetic person at the school, and his unisex given name helps him maintain the charade.

In terms of personality, Hibiki is idealistic and kind-hearted, possessing a strong sense of honor and a genuine passion for education. He is understanding and sweet towards his students, yet also capable of displaying a strong, manly resolve when the situation demands it. As a teacher, he functions as a psychologist figure who helps his students with both academic and personal problems, mediating conflicts and addressing the discipline issues that have arisen from the administration's prejudiced policies. His cross-dressing is framed positively, as he never uses his disguise for any perverted purpose; his only interest is being the best possible mentor for the young people in his charge.

However, Hibiki's situation grows increasingly complicated throughout the series. He must constantly navigate life in disguise, avoiding missteps such as accidentally using the masculine pronoun "ore" in front of the entire school, which nearly blows his cover on his first day. He also faces growing suspicion from the vice principal while simultaneously earning the adoration of his students. A significant challenge arises when one of his female students, the sweet and clumsy Fuko Kuzuha, develops romantic feelings for his female persona, leading to a complex and uncomfortable dynamic.

Hibiki's development reaches a critical turning point when he realizes that he is beginning to reciprocate these feelings for his fourteen-year-old student. This revelation disturbs him, and he acknowledges on multiple levels how wrong such a relationship would be, given that he is both her teacher and an adult. His relationship with Lulu remains key throughout, as she provides not only the tools for his disguise but also crucial support and comic relief, with her suspicion that she herself may have lived a similar experience. Eventually, Hibiki's true gender is revealed to the entire school, leading to his firing. Faced with this outcome and his dangerously close relationship with Fuko, he chooses to move away, hoping that the distance will help his student move on. Despite the bitter ending to his employment, he leaves a lasting, positive impression on his students, who genuinely hope for his return as his authentic self.