Inori Amano, a high school student burdened by low self-esteem, grapples with insecurities rooted in her appearance, academic struggles, and social isolation. Described as an outsider with a flat chest, freckles, and below-average grades, her perceived inadequacies in academics and athletics cement her status as an underachiever among peers.

A pivotal moment occurs when an extraterrestrial named Halley collides with her, fatally injuring her. During reconstruction, Halley inadvertently alters her physical and cognitive traits, enhancing her intelligence, athleticism, and bust size. These unintended changes trigger a surge in self-confidence and newfound attention from classmates.

Despite her transformation, her romantic feelings for classmate Sugiuchi anchor her motivations. Previously the sole source of kindness in her life, Sugiuchi’s compassion nurtured her affection, yet lingering shyness and self-doubt paralyze her ability to pursue him independently.

Driven by scientific curiosity about human reproduction, Halley seizes control of her motor functions, compelling her to initiate physical intimacy with Sugiuchi despite her reluctance. Though she vocally resists the alien’s influence, her actions mirror suppressed desires, weaving a complex tension between external manipulation and personal yearning.

Her journey navigates the fallout of her altered identity, as she balances external validation from peers with internal struggles over autonomy and self-acceptance.