Ayumi Futaba, the younger sister of Shotaro Futaba, lives with her family in Miyagi Prefecture during her second year of junior high school. She shares a close, affectionate bond with her brother, marked by mutual support and warmth. Though somewhat spoiled, Ayumi exhibits a sweet and caring disposition. She actively engages in Shotaro's life, showing particular interest in his rhythmic gymnastics activities at Ao High School. Her attentiveness to his new environment is evident when she expresses surprise after viewing the school dormitories online. Ayumi also holds a fondness for her mother's homemade gyoza, underscoring her family-oriented nature. Her given name "Ayumi" combines the characters for "second/Asia" (亜), "reason/cause" (由), and "beautiful" (美), while her surname "Futaba" signifies "pair/set" (双) and "leaf" (葉), collectively meaning "bud" or "sprout."