Manabu Odagiri attended elementary school with Oishi Neri and Amamiya Maya. Even then, she encountered Amamiya's manipulative behavior and resisted it, her fundamentally caring and genuine disposition contrasting sharply with Amamiya's exploitative tendencies.

Initially more academically inclined, Manabu showed greater interest in drawing manga than athletics. She admired Neri's inner resilience. Later enrolling at Kokuyodani High School, she joined the volleyball team despite possessing no prior experience or skill. Senior members recognized potential in her inherent kindness, thoughtfulness, and imagination.

Through dedicated training, these personal qualities gradually translated onto the volleyball court. Manabu evolved from an absolute novice into a proficient setter, developing strategic understanding and technical ability. Her journey emphasized organic growth tied to her personality rather than innate athleticism.

Her history with Amamiya Maya resurfaced significantly when Amamiya became captain of another volleyball team. Manabu instinctively recognized Amamiya's tactics of manipulation and social engineering. She reacted strongly to Amamiya's control over teammates, reigniting their childhood dynamic within the competitive sports context. This opposition revealed a determined, fiery aspect consistent with her otherwise gentle demeanor.

Manabu's bond with Neri was characterized as complementary and supportive, differing fundamentally from Amamiya's obsessive mirroring of Neri. This contrast positioned Manabu and Amamiya as distinct types of equals or counterparts in relation to the protagonist.

By later narrative stages, Manabu contributed to challenging Amamiya's influence. This occurred alongside interventions from older, more experienced characters who began identifying and confronting Amamiya's problematic behavior. Their combined efforts initiated the erosion of Amamiya's control over her team.