Lucy, a unique human known as a 'Diclonius' due to her horn-like protrusions and telekinetic abilities, becomes a victim of cruel government experiments. Seizing a chance to break free from her tormentors, the embittered Lucy unleashes a wave of violence during her escape, resulting in a head injury that fractures her psyche. Now, she exists in a childlike state with limited speech. Encountering two unsuspecting college students, Kouta and Yuka, Lucy's presence, shrouded in danger, alters their fates. Oblivious to her deadly alter ego, the duo extends compassion towards the wounded fugitive, setting off a chain of events that entangle them in a web of government secrets and intrigue.