"Nyotai-ka!" is a manga series that blends elements of comedy, romance, and science fiction. The narrative centers around Tetsuya Katori, a high school student who undergoes a bizarre transformation after being exposed to a mysterious chemical. This chemical causes his body to change into that of a woman, leading to a series of humorous and often awkward situations as he navigates his new identity.

The story explores Tetsuya's attempts to adapt to his altered physical state while maintaining his relationships with friends and family. His best friend, Akira, becomes a key figure in helping him cope with the changes, though Akira's own feelings and reactions add complexity to their dynamic. Tetsuya also encounters a scientist, Dr. Katsuragi, who is researching the chemical and its effects, providing a scientific backdrop to the otherwise comedic and personal struggles.

As the series progresses, Tetsuya's transformation becomes a catalyst for exploring themes of gender identity, societal expectations, and personal growth. The narrative delves into how Tetsuya's experiences challenge his understanding of masculinity and femininity, as well as how others perceive him. The interactions between characters are often driven by misunderstandings and the tension between Tetsuya's internal identity and his outward appearance.

The manga balances its comedic elements with moments of introspection, particularly as Tetsuya grapples with the implications of his transformation on his future and relationships. The series maintains a lighthearted tone while addressing deeper questions about identity and self-acceptance, making it a unique blend of genres that appeals to a wide audience.