Keisuke Uesugi is a teenage boy who has always struggled with feelings of inadequacy due to his small frame, adorable appearance, and average performance in school. These insecurities are magnified by the constant comparison to his childhood friend Eito Yaemura, who is tall, brilliant, and everything Keisuke feels he is not. The core conflict ignites when Keisuke overhears his other childhood friend and secret crush, Noel, say about him, "Wouldn't he be the cutest if he were a girl?". Crushed by the belief that Noel does not even see him as a viable male love interest, a desperate Keisuke makes a prayer at a local shrine, wishing for a single chance at young love. However, due to a misunderstanding, his prayer is granted in a literal and unexpected way: he wakes up transformed into a girl. The deity who answered his wish also imposes a specific rule for returning to normal; Keisuke cannot change back unless he finds the exact same 1000-yen bill that he used to make his offering, a task made nearly impossible since the shrine has already deposited the money in the bank. This predicament forces Keisuke to navigate daily life in a new female body while being caught in a confusing love triangle with Noel and Eito.

The story is set in contemporary Japan, a familiar world of schools, homes, and local shrines, but with a single magical realist twist involving a mischievous or literal-minded deity. The main cast revolves around the three childhood friends. Keisuke Uesugi is the protagonist, a boy who is small and cute for his age, and whose transformation throws his identity and romantic hopes into chaos. Noel is the object of Keisuke's affection, whose ambiguous comment sets the plot in motion; she shows little to no attraction to boys but responds positively to Keisuke in his new female form, adding layers of complexity to the romantic dynamic. Eito Yaemura is the tall, handsome, and brilliant best friend who serves as a constant source of Keisuke's insecurity, yet his role in the emerging love triangle suggests his feelings may be more than friendly.

The manga follows several notable narrative arcs. The story begins with the transformation arc, covering Keisuke's wish, the shocking physical change, and the initial discovery of the seemingly impossible conditions for reversing it. This leads directly into the adjustment arc, where Keisuke must navigate everyday life as a girl, dealing with issues of clothing, presentation, and the surreal experience of having long hair that magically restores itself when cut. The core of the series is the love triangle arc, as the dynamics among the three friends shift dramatically. Keisuke now finds himself in the position of having to choose between Noel, who only seems attracted to him as a girl, and Eito, his male friend. A significant plot point revolves around the lost 1000-yen bill, as Keisuke's quest to find it and revert to his original body serves as the overarching goal, though the deity's condition makes success seem almost impossible, suggesting that Keisuke may need to find a different kind of resolution than simply changing back.