In the not-too-distant future, a crop of humans emerge with extremely powerful mutations, lending them telekinetic abilities. Fearing the power that these new people possess, the government institutionalizes them at early ages or even birth, calling them dicloniuses. In these facilities, dicloniuses are cruelly experimented on until the day that they are executed. One diclonius, however, escapes. A young woman named Lucy, mired in hatred and rage from years of abuse, breaks free from the numerous forms of restraint placed on the facility and, killing some guards in the process, flees into the night. Lucy experiences some kind of psychological break during her escape, however, and when she is found, unconscious by Kouta and his cousin Yuka, her personality has split. Lucy's wrath is sectioned off into her existing personality, but another persona emerges in her that is innocent, gentle and so childlike that she even lacks the ability to speak. Kouta and Yuka call this sweet girl Nyu and decide to take her in. Eventually, other dicloniuses also find their way to the haven of their house, seeking refuge from the government.
Elfen Lied deals with the issue of human evolution but more strongly focuses on matters of trauma, identity, and compassion, begging the question of what kind of happiness Lucy/Nyu and all those with painful pasts can hope for. ~ Cammila Albertson, All Movie Guide