Seiji Yagiri left school in order to spend his life with a woman he claims he loves who resembles Celty's head. His older sister Namie had a part in making this girl who she is today and is hiding a terrible secret from her younger brother. The mystery of the Dullahan's head further become unraveled when Celty spots the girl in the streets with utter shock.
Opening Theme Uragiri no Yūyake ( 裏切りの夕焼け Sunset of Betrayal") by Theatre Brook
Seiji is treating the girl with Celty's head with a walk through the park while she appears to be trying to escape, contacting someone on her cell phone. She ends up tossing Seiji's cell phone in the fountain when he's not looking so that he can't be tracked. However, this act only makes Namie more annoyed because she can't keep in touch with Seiji. She plans to enlist Izaya's help in finding her brother, but Izaya cracks a few jokes with her before mentioning that Seiji and Celty's head had already been found by someone else. As Izaya wonders about the situation and tracks her brother through the internet, Namie reflects on how this all started.
Seiji obsesses over Celty, not caring he just killed Mika
Through flashbacks she reveals that she has romantic feelings for her brother Seiji, and snuck into her uncle's study room to look at his work. At one point, she saw that he had the head of a Dullahan in a jar on his desk, but she regrets the day when she invited Seiji to look at it, because ever since he first laid eyes on that jar he stopped caring about her and started to be obsessed with the head of the Dullahan named Celty. Namie of course became jealous of the situation and tried to have Seiji forget about the head in the jar and focus more on her. However, she one day discovers Celty's head to be gone and gets a call from her brother.
Namie and her associates arrive at Seiji's apartment where they find the dead body of Mika Harima, Celty's head, and Seiji acting nonchalantly about the whole thing, eating ramen while they assess the damage. Namie assures Seiji that she'll take care of everything and that nothing should be worried about. It is implied that Namie did surgery on Mika's body and replaced her head with that of Celty's so that her brother could finally find love and stop obsessing over the head and eventually come back to her, something Shinra may have had a part in. Izaya snaps her out of her flashback to state that Seiji is in police custody and that they will be calling her to come bail him out. Sure enough, her phone begins to ring as Izaya was right about her brother being in jail. As she leaves, Izaya mocks her in the sense that she lusts over her brother and is so jealous of something stupid like a head. Namie quickly shoots him down as she leaves.
Celty runs into the girl with her head in the park
The scene goes to show how Seiji landed in prison. At the local park, Celty and Shizuo are hanging out since they have a break in between their jobs. However, Celty see's the girl with her head as she runs and grabs her. The girl immediately freaks out and screams as Shizuo tries to calm her down. Instead, he is stabbed in both legs by Seiji with pens as the girl flees. Shizuo tells Celty to go ahead and he'll take care of Seiji. Celty is able to get after her head but the girl runs into Mikado, who he helps her to escape into the subway. Shizuo meanwhile is battling Seiji who stabs him through the hand with another pen. Shizuo discovers that Seiji knows practically nothing about the girl and throws him into a truck. He leaves as the police come, wondering how to deal with the pens in his body.
Namie is briefed on the situation as she informs her associates that she wants that head back dead or alive, granted she hints that she does not mind if the girl dies. She also tells them to take care of the Raira Academy student who was seen with her as they begin the search for Mikado and the girl.
The episode is told through the flashbacks and perspective of Namie.