Elfen Lied - Season 1 (2004)

Nana gets into a deadly fight with Lucy after tracking her down. Meanwhile, Kota suffers a diminishing relationship with Yuka, who has become jealous of Nyu. Yuka discovers that Mayu is homeless.

Kota and Yuka get custody of Mayu and start school. While at the University, a strange professor recognizes Nyu and, pretending to be her uncle, forces Yuka and Kota to give her up.

Kurama asks Nana to find Lucy with her powers of Diclonius. Yuka realizes Kohta does not remember his father died in a car accident or that they went to a festival together as small children. Nana finds Lucy.

Nana returns to Kamakura after Kurama disobeys orders to kill her. While there, she runs into Mayu and soon becomes friends with her.

After being briefly attacked by Nana, Nyu reverts to Lucy and catches a fever. While Nana tries to convince Mayu that she's dangerous, Lucy remembers her past as an orphan who was constantly bullied.

Still in her fever dream, Lucy remembers more of her past. By chance she met Kohta, the first human being to treat her with compassion and truly be her friend.

Kurama remembers his past. After graduating college, professor Kakuzawa offers him a chance at top secret research. While at the offshore facility, Kurama witnesses first-hand the terror of the diclonius.

Kurama leaves the facility to talk to Bandoh; they make a deal that involves the destruction of Mariko.

Mariko enjoys playing around with Nana since she is only allowed to kill her. Kohta arrives at the scene and Nana saves him by falling into the ocean

Nana almost falls into the ocean, but Kurama arrives to save her. Kurama tells Nana that he must kill Mariko and they go search for her.

Lucy and Nana draw closer together.