"A Sudden Turn" is the thirteenth episode of the Durarara!! anime and the fourteenth episode overall.
The episode begins with Celty Sturluson driving her motorcycle. At Raira Academy, everyone is looking at Seiji and Mika whispering about their love. On the roof, Masaomi groans about feeling jealous whenever he sees them. Mikado tells Masaomi to stop looking at the couple, but Masaomi starts hitting on Anri instead. Mikado then accidentally confesses that he thinks that Anri is cute. Anri runs into Nasujima in the school hallway, but Masaomi steps in before he can confront her.
In another part of town, Shizuo and Tom spot Walker and Erika climbing into Saburo's van. Celty is noticed by Shizuo, Tom, and Kyouhei's gang. A figure with bright red eyes is standing behind Shizuo, but when he turns to look, they are gone.
Shortly after, Celty is being chased by the police. One of the police officers was Kinnosuke Kuzuhara. Eventually, Celty is cornered by the police and Kuzuhara tells her that she, as a monster, should not mess with the law.
Some time later, Celty arrives home. Frightened, she hugs Shinra and tells him about her police chase, promising to be more careful from now on. Shinra, after hearing the story, asks her to pick up his father. Celty leaves to complete the job but is not pleased to do so.
In town, Horada and his crew are harassing Shinra's father, Shingen Kishitani, who is wearing a lab coat and a full-face gas mask. They mock him, and one thug pours his pop on Shingen's head. Shingen adopts an officious voice and berates the thugs in response. Horada then steps on Shingen's foot and stabs him with his thumb, causing Shingen to complain and ask Celty why she is not intervening.
Noticing Celty, Horada confronts her about her appearance on their territory at the Dollars meeting six months prior. Irritating by their lack of fear toward her, Celty traps the thugs' ankles in shadow but releases them so they can run away screaming, leaving her satisfied. As they run away, Shingen reverts back to his officious tone.
In another part of town, Namie punches a time card reading "Secretary" and walks in Izaya's office, seeing that he it out. She notices a strange board on his table with a shogi piece, an othello piece and a chess knight lying in the center, leaving her to question how Izaya plays the game.
Izaya is seen walking in the city when he runs into Simon, who offers him sushi. Simon then tells Izaya in Russian that he couldn't keep it a secret for long. Izaya responds in Russian before laughing and walking away.
Mikado, Masaomi, and Anri are walking home from Raira. While Anri in deep in thought about how she used to depend on Mika and she now depends on Masaomi and Mikado, Masaomi decides to list her qualities and tries to get a blushing Mikado to do the same. Masaomi decides to pick up girls and insists that Anri and Mikado come along, as Anri will be his bait, and he runs ahead. Mikado and Anri do not follow him but instead walk through a park that is presumably on the way home for both of them. Anri continues her thoughts on the way she depends on the boys. She asks Mikado if it was okay to leave Masaomi like that, and Mikado laughs and says that Masaomi will try to pick up chicks whether they are with him or not. Anri laughs and Mikado blushes. Trying to make conversation, Mikado point out the sunset and some approaching storm clouds, to which Anri does not reply. After a short moment of walking, she abruptly turns to Mikado and says goodbye. Mikado watches her leave, muttering that he isn't a smooth talker after all.
Masaomi walks through town, amused by Mikado's behavior around Anri and implying that he left the two alone on purpose. He notes a number of people walking around wearing yellow, and three of them confront him. They insist that they can't do anything without him, but Masaomi declares that he is not coming back and walks away.
Anri walks home, passing Mika and Seiji, but the three bullies wearing angel wings follow, kicking her down onto the curb and accusing her of 'whoring' herself to Mika, Mikado, Masaomi, and Nasujima. When they call her a parasite, Anri acknowledges to herself that those words are true. Frustrated by Anri's lack of response, the girls increase their bullying. Anri blocks out their words by retreating into her mind, only catching snippets of their teasing while telling herself that this is her daily life. She notices a shape forming behind the bullies, moving oddly and growing closer. Her breath quickens, but she repeats her mantra that this was her daily life, nothing changes, nothing happens. Red eyes loom behind the bullies, and from the place in her mind to which she's retreated, Anri watched the girls get cut by the Slasher as their blood sprays on her.
Kanra, Setton, and TarouTanaka talk about the increasing number of people around the city wearing yellow, and Setton identifies them as the Yellow Scarves. Kanra explains to TarouTanaka that they were a gang that was huge in Ikebukuro until they clashed with another gang and disappeared. Kanra mentions that the city has been getting scary lately, and Setton warns them not to mess with the cops. Kanra shares rumors that link the Slasher and the Headless Rider to the Dollars, upsetting Setton and TarouTanaka. In private messaging, Kanra advises TarouTanaka to watch out for the Yellow Scarves, as they dislike the Dollars because of the Dollars' growing size and influence in the time after the Yellow Scarves' disappearance.
Saika appears in the chat room using disjointed language and repeating the word 'cut.' TarouTanaka and Setton are annoyed by Saika, who has been trolling the chat room for the past six months, and Kanra promises that she's tried to block Saika's remote host several times before, but she keeps coming back. Setton admits to being creeped out as Saika repeats the word 'Mother.'
- The Slasher can be seen in the background stalking Shizuo.
- Simon Brezhnev
- Mika Harima
- Seiji Yagiri
- Masaomi Kida
- Mikado Ryuugamine
- Anri Sonohara
- Takashi Nasujima
- Shizuo Heiwajima
- Tom Tanaka
- Kyouhei Kadota
- Saburo Togusa
- Erika Karisawa
- Walker Yumasaki
- Celty Sturluson
- Kinnosuke Kuzuhara
- Shinra Kishitani
- Shingen Kishitani
- Namie Yagiri
- Izaya Orihara
- Who is the Slasher, and why were they watching Shizuo?
- What is Masaomi's connection to the Yellow Scarves?
- Who is the person trolling the chat room under the name 'Saika?'
Masaomi: "Those who laugh at the erotic, die by the erotic."
English dubbed version: "Live by the booby, die by the booby."