After spending the night with them, Mayu leaves. Mayu's past is revealed. Mayu's mother remarried, and her new stepfather repeatedly molested her. When her mother refused to help, jealous her husband was paying more attention to her daughter then her, Mayu ran away from home, where she encountered a stray dog she names "Wanta." In present day, Kohta and Yuka convince Mayu to come live with them. Mayu's mother happily gives Kohta guardianship of Mayu. When Kohta and Yuka return to their university classes accompanied by Nyu, Professor Kakuzawa, the son of Kurama's boss (and, by coincidence, a university lecturer) discovers Nyu. Claiming Lucy is his brother's daughter, he takes custody of her from Kohta and Yuka. Kakuzawa is revealed to be partly diclonius, and intends to breed with Lucy to end the reign of homo sapiens. However she decapitates him, claiming he is worthless in the evolution towards a diclonius-populated world. Her vector's have returned.