Aya is a good friend of Miki's. Though Aya doesn't have much interest in cycling and finds Miki's excitement over bicycles confusing, she still listens to Miki when she talks about her interest. Miki calls her "Aya-chan." Aya is very protective of Miki and is quick to strike any otaku that tries to converse with her, as well as anyone who makes perverted comments towards her.
Aya initially finds Onoda disgusting, but she later seems to develop a bit of respect for him. In the movie, she struggles at first, but congratulates him for his victory at the first Inter High. Before the second Inter High, she tells him to do his best.