Ayumi Futaba, a second-year junior high student in Miyagi Prefecture, is Shotaro Futaba's younger sister. She maintains a positive relationship with her brother and particularly enjoys her mother's gyoza.

Her given name "Ayumi" integrates the characters for "second/Asia" (亜), "reason/cause" (由), and "beautiful" (美). The surname "Futaba" combines "pair/set" (双) and "leaf" (葉), collectively meaning "bud," "sprout," or "twin leaf."

Personality assessments note Ayumi's detail-oriented nature, patience, and dedication to supporting others. She demonstrates loyalty and conscientiousness, consistently prioritizing others' needs while valuing traditional family principles. Her strong observational skills and memory lead her to analyze surroundings meticulously. Ayumi avoids conflict, seeks stability, and shows hesitance toward new experiences or risks.

Financial challenges in her family necessitate a part-time job alongside academics, resulting in persistent exhaustion. Despite this, she persists in pursuing her objectives.

In group settings, Ayumi assumes a supportive role by offering motivation and emotional reassurance to peers. This encouragement strengthens team cohesion.