Aiko is the daughter of a rich family who has been lying dormant for sixty days, and no doctor or priest would be of any help for her. Aiko was possessed by a shinma named Raen. Her parents died after donating all their blood to save their daughter, but this shinma deceives Aiko into thinking that she is a vampire living with her human parents. When Himeko goes to see Aiko again, Miyu arrives and pulls Raen out of Aiko, banishing it to the darkness, unfortunately killing Aiko in the process.
Aiko's parents were severely injured in a car crash. They had sacrificed their lives for her by giving their blood to her in order for her to live, which makes her terribly guilty; in her grief she claims to be a vampire, since their blood was donated to her after their deaths. Raen provides Aiko an illusionary home, parents and dreams, turning Aiko into a functional vampire who kills older girls and adult women. Miyu's attempt to save Aiko (by biting and making her a full vampire) is stalled by Himeko, and she and Larva end up exorcizing Raen, killing Aiko in the process.