The Diclonius, a mutated homo sapien that is said to be selected by God and will eventually become the destruction of mankind, possesses two horns in their heads, and has a “sixth sense” which gives it telekinetic abilities. Due to this dangerous power, they have been captured and isolated in laboratories by the government. Lucy, a young and psychotic Diclonius, manages to break free of her confines and brutally murder most of the guards in the laboratory, only to get shot in the head as she makes her escape. She survives and manages to drift along to a beach, where two teenagers named Kouta and Yuka discovers her. Having lost her memories, she was named after the only thing that she can now say, “Nyuu,” and the two allow her to stay at Kouta’s home. However, it appears that the evil “Lucy” is not dead just yet…Having been accepted into the Kaede Inn, Nana struggles to find some way to contribute, though she inadvertently brings more trouble than assistance. However, Nana’s worries are directed more towards fellow resident Nyu, whom she had only known as Lucy, the violent Diclonius. Fearful that Nyu will unleash the same horrific savagery—violence that scars Nana to this day—upon those close to her, Nana faces a dilemma: attempt to live peacefully alongside Lucy with all the uncertainty that that entails or dispose of the source of her worries, shattering the relationships she has formed at the inn. As Nana struggles to come to a decision, Nyu recalls a painful memory of one of her dearest friends and one of her greatest rivals.