Kouta's efforts to explain his awkward position with the undressed Nyu are met with resistance and dismissal from Yuka, culminating in her furious departure, with her even slapping him when he fails to remember a festival the two attended as children. To make matters worse, Kouta realizes he has caught a cold.
In her home, Yuka sits and remembers her childhood times with Kouta while staring at some carvings she keeps in a box. In the memory, young Kouta teases her about her lack of skill at the festival carving games compared to his smooth ease at doing them. He vows to obey whatever wish she puts forward if she gets better at these games, and she pledges to remind him of this promise. In the present, she cries and breaks some of the carvings she made over the years to show him, cursing herself as an idiot.
At the island research facility, Shirakawa and Isobe watch Nana and Kurama, commenting that Nana is not his real daughter, this despite calling him 'Papa.' Nana, or Number Seven, has endured her hellish life by attaching to Kurama for mental support. She remains unique in her steadfast refusal to use her vectors against Humans. Inside the chamber, Nana insists she will do whatever Kurama asks of her, till he raises the subject of killing someone. He lets her know the target is not a Human, but another Diclonius, yet she insists she still won't kill. Kurama amends his request to merely finding and capturing this person. Nana asks if they are someone who has bothered her 'Papa,' and Kurama responds that they are and that he must depend on Nana to find her and report in when she does. Nana proudly says that for him, she will do her best. Kurama orders his assistants to prepare Nana for departure by the next day.
At Maple House, a feverish Kouta tries to rest, distracted by the still half-naked Nyu and in desperate need of water, about which the childlike Nyu seems to have no clue. Yuka returns with some clothes she had brought for Nyu and is pulled inside by a frantic Nyu, finding Kouta in need of attention inside a room full of the items Nyu pulled in trying to get water for him. Thinking the unusual arrangement is some manner of a charm, Yuka applies moistened towels to Kouta's head to help break his fever, which he says he does not want to go to the hospital. Kouta apologizes for not remembering the festival, telling Yuka that the shock of the consecutive losses of his father in an accident and his little sister to illness made his memories of those times unreliable and vague. Yuka immediately realizes something is wrong, stating under her breath that this is not how his family members died. Fleeing the room under an excuse to change the water, she begins to cry once again, this time at the knowledge that Kouta's lack of memories isn't from callousness, but from traumatic stress.
Elsewhere, Kurama listens as the recovering, but severely wounded Bando rages against Kurama's assertion that Bando must undergo testicular castration to protect the world. Bando also demands to know who and what defeated him. Kurama explains the Diclonius, a Human evolutionary offshoot gifted with invisible arms called 'vectors,' aiming to spread their genes, with Lucy the only one capable of true reproduction. While these vectors, capable of lifting and cutting, can and are used as weapons by the Diclonius, their primary purpose is to spread the virus involved in the Diclonius mutation/evolution and infect the genes of the man affected, so as to accelerate the replacement of non-Horned Humans with Diclonii. Bando realizes that this means he is one so infected.
At Maple House, Kouta wakes to find Yuka hovering over him, much calmer than before, even touching her forehead to his to determine that his fever has broken. When Kouta refuses to involve the police in the mystery of Nyu's identity, Yuka also resolves to move in, owing to the awkwardness of him living alone with Nyu, who beams at him in the new clothes Yuka has given her.
At the island facility, Nana is delighted by her new clothes and is warned by Kurama to break off the mission should things get rough. Nana makes a request of him before her chopper leaves the island, with Shirakawa worried that Nana is no match for Lucy. Kurama states that her ability to sense Lucy makes Nana a resource they must use.
At Maple House, Yuka warns Kouta against 'strange thoughts' derived from living with two women, which Kouta denies is the case while picking up the pace of his cleaning, to the point he bumps up against Nyu's breast. At first scared, she then pulls his hand to her breast and makes him squeeze it. A smiling Yuka appears and once again rejects Kouta's explanations, slapping him while again warning him against 'weird stuff' with Nyu while she goes shopping. On her way out, she does not notice the girl and her small dog from the night at the beach, returning the umbrella with Maple House's address on it. Kouta talks with the girl and realizes she can confirm that he did not imagine soldiers on the beach during that incident. Yuka returns, sees the small pup outside the house, and wonders to who it belongs. At first thinking the worst of Kouta at seeing yet another girl there, Yuka is also intrigued by her account of the events of the night they searched for Nyu. While the thought angers Kouta, the police knew and lied about the soldiers' presence, in the nearby hallway Nyu is intrigued by a wooden box, but fails to take the polished, waxed floor into account, then slips and falls. When the concerned trio from the other room check on her, it becomes apparent that Lucy has reemerged. Her vectors fly out to kill Kouta but stop short when she recognizes him, with the image of a younger Kouta yelling at her to stop. She brushes past the others and leaves. Yuka asks the girl about her dog, and the girl responds that the dog is more like her friend. Yuka also reveals that the box Nyu was holding belonged to Kouta as a child and that she had held onto it since then. Kouta still can only remember a little about it.
Once outside, Lucy listens to the dog bark and uses her power on it for an unseen purpose. Back inside, the two are concerned for the departed Nyu but are confident she will come back, with Yuka nervously laughing off mention of her horns. The girl tries to excuse herself, but Kouta asks for her name, address, and phone number, in case he wishes to know more of what she knows about that night. The girl reveals her name is Mayu, but nervously walks out before answering anything more. Outside, Mayu falls into a panic when the dog she calls Wanta is not in sight, though he finally comes running up as she notes his cut leash. Amidst the joy of finding her only friend, Mayu does not pursue this mystery any further. Back inside Maple House, Nyu still hasn't returned, resolving Kouta to go and look for her. Yuka is sulking, begins to talk about the box from Kouta's childhood, and then stuns him by asking if he wishes to have his way with her breasts, as she believes he did with Nyu's.
On a stairwell leading down overlooking Jouju-in Cemetery, Nana recalls asking Kurama for his necktie, something she has always wanted. She ties it on her head like a band, and gingerly approaches Lucy, who also sensed her presence, flatly and matter-of-factly telling her that she has come to re-capture her.
|“||It became a place without reason or meaning. Only the inevitable strife of a species born to bite and tear itself to pieces. A mortifying banquet of blood and tears held at the peaceful sanctuary of resting souls. On the next Elfen Lied, Episode Four : Attack.||”|