Nagisa Minase is a first-year high school student and a classmate of Naoya Mukai and Saki Saki. She becomes the second heroine of the story after confessing her feelings to Naoya and entering a polyamorous relationship with him and Saki. Before meeting Naoya, Nagisa was a plain, unremarkable girl who wore glasses and kept to herself. Her transformation began when she witnessed Naoya’s unwavering dedication to Saki; inspired by his earnestness, she decided to remake herself. She changed her hairstyle, switched to contact lenses, and began rigorous training in sports and housework, determined to become someone worthy of admiration. Physically, Nagisa has short blue hair and blue eyes, often tied with a blue ribbon, and she is of smaller stature with a noticeably larger bust.

Nagisa’s personality is marked by a collected, considerate, and humble demeanor. She is deeply earnest and clumsy in her efforts, but her sincerity is matched by a willingness to use underhanded tactics when she feels her relationship with Naoya is threatened. Despite her sweet and supportive nature, she carries lingering insecurities from her past as a plain girl, which sometimes drive her to overcompensate. Her primary motivation is her love for Naoya, whom she regards as an inspiration. She constantly strives to be a better person for his sake, though this single-minded focus often leads her to prioritize his happiness above her own well-being.

In the story, Nagisa occupies the role of Naoya’s second girlfriend, a position that places her in a complex dynamic with Saki Saki. Initially rivals in love, the two girls develop a friendly and cooperative relationship as they navigate their shared romance. Nagisa admires Saki’s qualities and works to coexist with her, though occasional jealousy and competition surface. Her relationship with Naoya is both her anchor and her source of internal conflict; she looks to him as a role model while fearing that she cannot measure up to his idealized image.

Nagisa undergoes significant growth over the course of the series. Her decision to change her appearance and lifestyle marks the beginning of a journey toward self-improvement. She becomes highly proficient in athletics and domestic chores, demonstrating remarkable dedication and stamina. However, the time and energy she devotes to these pursuits cause her academic performance to suffer, creating an ongoing struggle to balance her ambitions with her responsibilities. Key moments in her arc include confronting her own insecurities, learning to trust both Naoya and Saki, and accepting that she does not need to be perfect to be loved. Through these experiences, she evolves from a shy, self-doubting girl into a more confident and capable young woman who actively shapes her own path.