Isara Aomi is a first-year student at Takafuji Private Academy, residing with her mother and two younger brothers in a single-parent household facing financial hardship. To secretly support her family, she works multiple part-time jobs, including shifts at a factory and a fast-food restaurant. This economic status qualifies her for the school's financial aid program, making her a target for persistent physical and verbal bullying from wealthier students. Despite the mistreatment, she maintains a respectful, kind, and friendly demeanor, often responding with smiles to conceal her distress and avoid burdening others.

Her responsibilities extend beyond work. Previously managing household duties in place of her working mother, she became skilled in domestic tasks like cooking. She exhibits diligence in all obligations, exemplified by enduring bullying while changing school light tubes and returning late at night to finish the task. Academically, she cycles to school and maintains a slim physique. She stands 160 cm tall with brown hair styled in long, wavy twin tails and violet eyes.

Though financial aid restrictions prevent official membership in the Food Research Club, she actively supports its activities and campaign efforts. Her interactions with club members, particularly protagonist Yūki Ōjima, gradually help her confront internalized acceptance of bullying and develop greater self-worth beyond her role as a provider. Her character arc explores themes of discrimination and resilience, highlighting how systemic biases affect student dynamics and campaign politics at the academy.

Prior to Takafuji, household commitments left her with no romantic relationships; later, her financial status led to rejection from male students. Her name "Isara" combines characters meaning "clothing/garment" and "new/obvious," while "Aomi" derives from "blue" and "sea," with the latter's pronunciation adjusted in English translation.