Aiko is a normal teenage girl, who comes home one day to find that a monster known as a chimera has killed her parents. She is attacked too, and her body is taken away to the morgue. However, it turns out that she is not dead, or perhaps has revived. Her arm, however, has been replaced with one containing material exactly like that of the chimera that killed her parents...The organization that found her body wants to dissect her to find out how this is possible. Aiko’s other option: join Atheos to fight the chimera, which she does once she has discovered how much she really wants to live.