Akira Uehara is the main protagonist of this story. He is introduced as a high school student who is, by traditional standards, a very gentle and effeminate young man. He is described as shy, kind, and demure, possessing a personality that is much more delicate and sensitive than what is typically expected from a boy his age. He is also neat, tidy, and enjoys cooking, which further sets him apart from more stereotypically masculine peers. Despite his soft nature, or perhaps because of it, Akira has developed a deep and sincere crush on his classmate, Nanako Momoi, who is known for being aggressive and violent.

Akira's life is turned upside down when he visits Nanako's home to deliver her homework. There, he encounters her grandfather, an eccentric and mad scientist-type inventor, whose experiment goes awry. As a result of the accident, Akira and Nanako swap bodies. This event is the central conflict of the story, forcing Akira to navigate life in the petite and beautiful body of the girl he loves.

In his new form, Akira's inherent gentleness combines with Nanako's attractive appearance, making him extremely popular and admired by his peers, a stark contrast to the fear that Nanako herself once inspired. This situation is a source of constant discomfort and frustration for him, as he is adamantly opposed to remaining in a female body and is desperate to return to his original self. His primary motivation throughout most of the narrative is to find a way to reverse the body swap and reclaim his old life. He struggles with the threat that Nanako, who is enjoying life in his stronger male body, will abuse her power and do terrible things to his reputation if he does not comply with her wishes. He also worries about the long-term effects of living as a girl, fearing that he might gradually lose his inner masculinity.

Akira's role in the story is that of the reluctant protagonist, whose life is thrown into chaos by forces beyond his control. The narrative follows his perspective as he deals with the daily humiliations and unexpected small pleasures of being a girl, while trying to keep his true identity a secret. His key relationships are all profoundly affected by the body swap. His relationship with Nanako Momoi becomes a tense and often antagonistic partnership, as they are bound together by their shared secret but have opposing goals; she is thrilled with the change while he is miserable. His best friend, Shinnosuke Senbongi, becomes a major source of anxiety for Akira. Senbongi learns the truth about the swap but instead of being repelled, he becomes romantically attracted to Akira in his female form, putting Akira in an extremely awkward position. Within his own family, the change is ironically positive; his parents and sister, who were previously disappointed in his perceived lack of manliness, are pleased with the improvement in "his" character after Nanako takes over his body.

Throughout the series, Akira undergoes significant character development. He begins as a boy who is desperately trying to hold onto his identity and reverse the swap. However, as time passes and he sees how everyone around him, including Nanako, seems happier with the new arrangement, his resolve begins to waver. He eventually comes to a reluctant acceptance of his situation and resigns himself to living in Nanako's body, believing that the new status quo is ultimately for the best. In terms of abilities, while not possessing any superhuman powers, Akira is noted for his domestic skills, such as cooking, which make him a valuable asset in the Momoi household and endear him to Nanako's lazy grandfather.