Hazumu Osaragi is the central protagonist of her narrative, a character whose life is irrevocably changed by an extraordinary accident. Initially introduced as a gentle and somewhat effeminate high school boy, Hazumu possesses a deep passion for gardening and a kind, selfless nature that prioritizes the happiness of others. This sensitivity, which made Hazumu a target for bullies during childhood, also informed a deep-seated but perhaps unacknowledged alignment with femininity. Even before the pivotal transformation, Hazumu’s demeanor was notably soft, and there were hints of a female identity, such as a childhood wish to become her friend Tomari's bride.

The story’s catalyst occurs when Hazumu, after being rejected by a classmate named Yasuna, wanders up a mountain in distress. There, Hazumu is fatally struck by a crashing alien spacecraft. The alien responsible, Hitoshi, restores Hazumu to life but inadvertently reconstructs the body as completely and irreversibly female, down to the genetic level. This dramatic change serves as the central premise. Rather than experiencing distress or a desire to return to a male form, Hazumu adapts to the new body with surprising ease, often suggesting that this transformation aligned with an innate sense of self. While Hazumu continues to use the masculine pronoun boku, the personality remains consistent: kind, timid, effeminate, and endearingly indecisive, especially when it comes to matters of the heart.

A significant part of Hazumu’s arc involves navigating the practical and social aspects of living as a girl. This includes learning about feminine clothing, etiquette, and navigating spaces like the school locker room, often with guidance from female friends. This journey of adjustment is intertwined with a deepening romantic complication. Yasuna, who originally rejected Hazumu, reveals she suffers from a condition that prevents her from seeing males clearly. Because Hazumu was the only boy she could perceive, and now is a girl, Yasuna professes her love. Simultaneously, Hazumu’s childhood friend, the athletic and protective Tomari, struggles with her own evolving feelings, moving from a platonic protector to a romantic rival for Hazumu’s affection. This creates the central love triangle that drives the emotional core of the story.

Hazumu’s primary motivation is a desire for connection and the happiness of those around them. This selflessness, however, fuels a deep indecisiveness, making Hazumu incapable of easily choosing between Yasuna and Tomari. The role in the story is that of a catalyst for exploring themes of love, identity, and acceptance, as Hazumu’s very existence challenges the assumptions of friends and classmates. Key relationships beyond the romance include a close friendship with Asuta, a male friend who finds himself unexpectedly attracted to the new Hazumu, and a more observational, supportive bond with Ayuki. The relationship with the alien Hitoshi and his AI companion Jan Pu is also significant, as they are responsible for the transformation and remain on Earth to study Hazumu’s emotional development.

Throughout the series, Hazumu’s development is marked by a growing comfort and confidence in a female identity, moving from initial cluelessness to a more natural embrace of this existence. The narrative diverges in its conclusion; in the primary anime storyline, Hazumu chooses Yasuna, while the follow-up OVA and the original manga ultimately see Hazumu confess love to and marry Tomari. In terms of abilities, aside from a profound knowledge of horticulture and a naturally nurturing disposition, Hazumu possesses no special powers or skills. The key capability is an emotional resilience and an open-hearted kindness that draws people in, even as Hazumu’s own indecisiveness causes conflict.