Lucy and Nyū

Nyu

Nyu is an alter ego of Lucy that emerged after a .50 BMG round pierced the metallic helmet encasing her head during her escape. Nyu exhibits a childlike personality and infantile knowledge of the world, initially lacking spoken language skills and able to say only "nyū" and later "Kōta". As the series progresses, her vocabulary expands; by the halfway point she can speak normally, though she still occasionally says "Nyu". She is innocent and incapable of violent acts, serving as a foil to Lucy.

When Nyu is attacked or hit on the head, she regresses into Lucy; conversely, when Lucy is treated with love and kindness, or wishes to hide herself from Kōta, she changes back into Nyu. While Nyu initially exists due to trauma, Lucy subconsciously encourages her presence because of her guilt toward Kōta and to prevent herself from harming him further. Nyu cuts her hair to resemble Kōta's deceased younger sister Kanae, whom he had spoken harshly to before she was killed by Lucy; this haircut was the same one Lucy had eight years earlier, causing Kōta to vaguely remember her.

Nyu suppresses Lucy for much of the series' end after one of Lucy's horns is damaged, but Lucy reemerges in her second fight with Bando. Nyu returns in chapter 83, when Lucy's horns grow back larger and her vectors become much longer, allowing her to reach a flying helicopter as she slaughters soldiers in front of Kōta after he is critically injured, causing him to remember that she killed his family. After her horns are damaged again, she is captured and brought to Director Kakuzawa, who reveals his plot to terminate mankind and fill the world with Diclonii, attempting to convince her to join him.

Despite still being Nyu, she uses her vectors and later, as Lucy, kills him. She escapes the sinking island to face Kōta once more.