A young girl approaches Tenchi Masaki and calls him "Daddy," causing his world to be turned upside down. Initially, he thinks the girl has confused him with another man, but he takes her home to uncover the truth. Unfortunately, this mistake triggers chaos in the already chaotic Masaki household when the girl identifies herself as Mayuka Masaki, Tenchi's daughter. Although DNA testing confirms Mayuka's relationship to Tenchi, the other girls refuse to believe it, suspecting that Mayuka is manipulating him. Washuu, however, believes that Mayuka is a product of a recent time distortion incident from the future. Once this revelation comes to light, everyone tries to include Mayuka in their lives except for Ryouko Hakubi, who senses a lurking malevolence behind Mayuka's pleasant demeanor.