After witnessing her family's slaughter, Aiko is startled to awaken on a laboratory table, seemingly unharmed. However, upon noticing the grotesquely disfigured arm grafted to her body, she quickly realizes that the life she knew before the attack is gone. Infused with the DNA of a mysterious monster called Chimera, the arm acts on its master's impulses, leaving Aiko unable to stop it. Alone and terrified, how will she cope with this dreadful fate?