Takeru Ohyama, a student at Tenbi Academy, finds himself in an unusual predicament after a mysterious incident transforms him into a woman. The story begins with Takeru and his classmates, including Inaho Kushiya, Kodama Himegami, and Aki Nijou, embarking on a school trip to a southern island. The trip takes a bizarre turn when Takeru accidentally consumes a potion created by Inaho, which causes his gender to switch. This transformation complicates his interactions with his peers, particularly as he navigates the dynamics of friendships and rivalries within the group.

The island setting serves as a backdrop for various comedic and action-oriented scenarios, often involving the use of "Maken," magical weapons wielded by the students. Takeru’s transformation becomes a central focus, as he struggles to adapt to his new identity while maintaining his relationships. Inaho, known for her eccentric inventions, attempts to reverse the effects of the potion, but her efforts frequently lead to further chaos. Kodama, a skilled swordswoman, and Aki, a disciplined martial artist, provide both support and competition, adding layers to the group’s interactions.

The narrative explores themes of identity and camaraderie, with Takeru’s gender-swap serving as a catalyst for humorous and occasionally introspective moments. The series balances lighthearted comedy with action sequences, as the students face challenges that test their abilities and bonds. Takeru’s journey to regain his original form drives the plot, while the island’s tropical environment amplifies the series’ playful and adventurous tone. The characters’ personalities and relationships are central to the story, with each contributing to the dynamic and often unpredictable events that unfold during their time on the island.