Nonoka Mamiya is a supporting character in the anime Aria the Scarlet Ammo AA and the younger sister of the main protagonist Akari Mamiya, being two years her junior. She is a middle school student who, unlike her older sister, does not attend Tokyo Butei High and is not a Butei cadet, attending a regular school instead. Nonoka has shoulder-length dark-brown hair, white skin, and violet eyes, and is often seen wearing a white blouse with a vanilla jacket and skirt. Her personality is marked by kindness, a supportive nature, and a level of maturity beyond her age, frequently taking on household responsibilities such as waking up her clumsy older sister and managing domestic chores. Despite her younger age, she acts as a stabilizing presence in the Mamiya household and is deeply caring toward her friends and those close to her. Nonoka holds great admiration and respect for her sister Akari, viewing her as a role model and striving to support her in any way she can, while Akari reciprocates by looking after her with sisterly guidance and care. Within the story, Nonoka plays a modest but meaningful role as a source of emotional support and familial grounding for Akari. She is also secretly appreciated by Akari's close friend Shino Sasaki, who takes a liking to her. Although she is not training to become a Butei, Nonoka has inherited the traditional techniques of the Mamiya family from her mother, and she applies these skills in practical, everyday situations such as when she is rushing to avoid being late for school. A notable event from her past involves an encounter with the I-U Special Combat Team two years prior, during which she was injected with a coded poison by an operative named Oleander; this incident has lingering consequences and becomes relevant when a bus jacking involving a so-called Butei Killer occurs. Nonoka is also revealed to be a skilled shooter, demonstrating impressive accuracy with a firearm when the situation demands it, which highlights a natural aptitude for combat-related abilities despite her non-Butei status. Her overall role in the narrative centers on her relationship with her sister, her quiet competence, and the underlying strength she possesses as a member of the Mamiya family, contributing to the themes of loyalty and family bonds that run through the series.