Nyuu is a central character in the anime series Elfen Lied. She is an alternate personality of Lucy, the main protagonist, who is a Diclonius—a new species with invisible telekinetic arms. Nyuu emerges after Lucy suffers a head injury, resulting in a childlike, innocent, and non-verbal persona. Throughout the series, Nyuu's gentle and naive demeanor contrasts sharply with Lucy's violent nature, creating emotional tension and highlighting the tragic duality of her character.