Aya Fujisaki attends Sainan High School, progressing from class 2-D to 3-D. She possesses blue hair styled with square bangs and chest-length side strands, purple eyes usually hidden behind large round glasses, and stands 157 cm tall weighing 47 kg with measurements of B81-W54-H81.

Her background includes childhood bullying, stopped by Tenjouin Saki and Kujou Rin's intervention. This event forged her absolute loyalty to Saki, whom she reveres as "Saki-sama." Aya is constantly present beside Saki and Rin, serving primarily as their supportive follower. While fundamentally shy and weak-willed, she exhibits fierce protectiveness towards Saki, reacting with intense anger to perceived threats like Yuuki Rito's accidental perversions involving Saki or Rin.

Aya displays no romantic interest in Rito, unlike many peers. Her focus remains solely on serving Saki, interpreting her wishes and acting as her attendant. Despite her unassuming nature, she demonstrates unexpected competencies, including operating heavy machinery like cranes (shown in anime-original content), piloting helicopters, executing complex binding techniques, and advanced cooking.

Her relationships are defined by her subservient dynamic with Saki and her association with Rin. Though she and Rin share a history of protecting Saki and coexist as friends, their interactions almost always occur within Saki's context. Aya's role across all official media, including seasons and OVAs, remains consistently that of a background supporter. In "Motto To Love Ru" Episode 5, she actively aids Saki's scheme to attract Zastin by assisting in coercing Rito, reflecting her unwavering dedication to Saki's goals. Her narrative function centers on reinforcing Saki's leadership through steadfast devotion.