Lucy is a unique human known as a "Diclonius," born with short horns and invisible telekinetic hands, making her a victim of inhumane scientific experiments conducted by the government. However, when the opportunity arises for her to escape, Lucy, twisted by her mistreatment, unleashes a wave of bloodshed upon her captors. But during her escape, a devastating head injury causes her to develop a split personality, resembling that of an innocent child with limited speech. In this fragile state, she meets Kouta and his cousin Yuka, two college students who unknowingly take in a wounded fugitive without knowledge of her violent tendencies. This act of kindness will thrust them into a dark world of government secrets and conspiracies, forever changing their lives.