Efen Lied

The story begins with a young girl named Lucy escaping under odd circumstances from an insular research facility off the coast of Kamakura in the Kanagawa Prefecture of Japan. Lucy manages to nonchalantly dismember and slay a fair number of the staff and guards with a form of seemingly supernatural power and gets outside. A sniper is seen trying to shoot her, only managing to ricochet a bullet off her metal helmet. Lucy then falls off a cliff into the sea, bleeding from her head but ultimately surviving and evading the research staff.

Lucy is not a normal human but rather a diclonius: a mutant variant of humans with two small horns on their heads (hence the name diclonius) that resemble cat ears. The diclonius race possesses telekinetic powers through use of their "vectors", long arms that resonate at a speed that causes them to be undetectable by sight. The number and reach of the vectors depend on the diclonius. All diclonius seem to be girls only. There is not one mention of a male diclonius throughout the whole series. They also all have pink eyes and hair unlike regular humans who have brown, black, blonde, and red hair.

The day after Lucy's escape, a boy named Kohta arrives at Kamakura to meet his cousin Yuka. Kohta has come to study at the local university and has been given lodging at an old, family-owned inn, the "Maple (楓, Kaede?) Inn", provided he acts as the caretaker. After meeting with Yuka, they go for a visit to the beach and find Lucy washed up on the shore, still naked and bleeding from her head. The head trauma Lucy experienced causes her to develop a split personality. In stark contrast to the cold and sadistic Lucy, this personality is completely docile, harmless and is incapable at first of saying anything other than "Nyu". Not knowing what to do with her, Kohta and Yuka take her back to the inn to look after her and name her "Nyu". Yuka quickly decides that it will be best that she also live at the inn.

Kohta, Nyu, and Yuka begin settling into their life at the inn and Nyu begins to dredge up painful repressed memories from Kohta's past. Meanwhile, the researchers from the laboratory where Lucy was held begin searching for her, dispatching both human and diclonius agents to hunt her down.