Ai is a young Lost Precious thief with werewolf-like abilities.
Despite her werewolf like abilities, Ai was actually born as a human to a Lost Precious collector named Makihara. She was kidnapped as an infant by a former Society researcher by the name of Furumori who was kicked out of the Society for experimenting with implanting Lost Preciouses into humans, a practice which he continued on himself and Ai. These are experiments are responsible for her werewolf-like abilities and the markings on her body. As a teen, Furumori trained Ai to use her abilities in order to steal Lost Preciouses under the guise of sharing them with the world.
Ai meets Ryuji Kisaragi at a Society gala where she has been sent by Furumori to steal the Lost Preciouses of the people there. When she is unsuccessful at capturing True Love from Eriko Nanao, she decides to break into her and Ryuji's house to retrieve it. Eriko, Rose and Ryuji are able to stop her, but Furumori shows up in disguise to finish the task, kidnapping Ryuji along the way. Back at their base, Ai secretly uses True Love and discovers that Furumori has been using her. She mounts an escape with Ryuji where they defeat Furumori. After their battle, she finds out about Makihara and decides to rekindle their relationship.