Fumino Furuhashi excels in literature and humanities as a third-year student at Ichinose Academy, earning her the title "The Sleeping Beauty of the Literary Forest" for crafting emotionally resonant essays and analyzing conversational subtext. This literary prowess sharply contrasts with her severe struggles in mathematics and science. Exposure to complex equations triggers an involuntary sleep response, humorously termed "mathematical hypersomnia," serving as a coping mechanism.

Her background involves personal tragedy, marked by her mother's death during childhood. This led to a decade-long estrangement from her father, Reiji Furuhashi, a university mathematics professor. Their strained relationship stemmed from his initial discouragement of her astronomy aspirations and neglectful behavior, including communication limited to written notes. The rift deepened when he unfavorably compared her to her mother, an incident he later regretted. With support from her tutor and confidant, Nariyuki Yuiga, Fumino confronted her father, leading to reconciliation. A pivotal discovery of a laptop containing her late mother's video message reaffirmed Fumino's dreams and mended their familial bond.

Fumino's personality blends empathy, introspection, and self-sacrifice. She keenly observes others' emotions, often advising Nariyuki on romantic matters involving other girls, even while suppressing her own feelings for him to protect her friends. Her interests include stargazing—a passion tied to her belief that her mother resides among the stars—and discussing zodiac signs. She enjoys sweet and spicy foods but feels self-conscious about her weight, cooking skills, and physical appearance. Academically, she persists in pursuing astronomy despite her mathematical weaknesses, demonstrating quiet determination.

Her character development centers on emotional growth and relationships. Initially reserved and isolated by her popularity, she gradually opens up through interactions with Nariyuki. Key moments include multiple stargazing dates bonding over shared interests, an accidental overnight stay at an inn deepening their connection, and temporary cohabitation blurring lines between friendship and romantic partnership. During a school play adaptation of *Sleeping Beauty*, she unknowingly kissed Nariyuki while he wore a mascot costume, an incident highlighting her subconscious affection.

In the manga's narrative conclusion, Fumino experiences a dedicated ending where a broken leg before a crucial exam forces reliance on Nariyuki. This proximity allows their mutual feelings to surface, culminating in a romantic relationship. Across all media, her journey emphasizes reconciling familial wounds, pursuing dreams against academic odds, and navigating unspoken romantic emotions with gradual assertiveness.