A classmate and friend of Kiiko. She likes to perform experiments with Kiiko's powers, but in reality she is in love with her. For one of the experiments she made two joined wire stars and told Kiiko to try and separate them. She usually takes the lead when it comes to activities and has an outgoing personality. She lives with her brother.
Aaya's brother had manipulated her into having sex with him before he dies, and Kiiko catches them on the move. Kiiko separates the wire stars by accident because she was extremely shocked by what she saw. They obviously broke up and lose touch with each other after that. One day Aaya locks herself up with Kiiko in a storage room without explaining anything to her. They have sex, while Aaya is half-raping Kiiko, but in the morning she escapes the storage room.
Because Aaya had decided to study abroad, she convinces Kiiko to have sex with her before she leaves Japan. Kiiko reads Aaya's memories in her own dream and understands why Aaya had to sleep with her brother. By that time, Aaya had already boarded on the plane. She took one of the separated wire stars with her, while Kiiko had one too. Kiiko is able to join the wire stars and teleport herself to Aaya's plane.(Source: Wikipedia)