"Rampant Evil" is the third episode of the Durarara!! anime.
Two Russian girls on spring break ask Simon for directions outside of Russia Sushi. At Raira Academy, Anri Sonohara and Mikado Ryuugamine volunteer to be the Class Representatives. Mikado talks to Anri after class, but their conversation is cut short when Anri sees a teacher coming toward her. Masaomi Kida arrives, telling Mikado that he and Anri are very cute together, along with some hints on how to make her love him. As Masaomi tries to pick up older women after school, Mikado hears a rumor that the Dollars have been behind slashing attacks recently. The friends run into Kyouhei Kadota, Erika Karisawa, and Walker Yumasaki. They tell Mikado to stay away from the Dollars, then Erika and Walker try to decide whether or not the Dollars are at war with Flame Haze and whether Kyouhei is an older brother character or a father character.Tom Tanaka and Shizuo Heiwajima are walking down the street when they see Celty Sturluson. Tom remarks that, "it's too early for scary things." Seiji Yagiri and Anri separately look for Mika Harima, and Anri finds a girl within a crowd, thinking it's her, but when she sees the girl's face she realizes she was mistaken and apologizes for grabbing her. Anri then runs into a trio of female bullies who seem to know her. They pull her aside in an alleyway and corner her, mocking her now that Mika is gone. One of them calls over their boyfriend, Hiroshi, to intimidate Anri.
Mikado sees the bullying and wants to help, but just when he decides to help, Izaya Orihara arrives and pushes Mikado in front of the bullies. Izaya declares how "lame" he considers bullying to be, and although he doesn't want to fight girls, he takes one bully's cell phone and smashes it. As Hiroshi takes a swing at him, Izaya shaves Hiroshi's head with his switchblade.
Sitting on a park bench after Hiroshi and the three bullies have run away, Izaya talks to the three of them, greeting Masaomi as an acquaintance, which surprises Mikado. Masaomi introduces Mikado to Izaya, and Mikado recognizes Izaya's name as one of the people Masaomi warned him not to cross. Masaomi asks Izaya what he is doing in Ikebukuro, and Izaya responds that he came to see someone while staring at Mikado pointedly when he is suddenly hit by a flying trash can.
A man in a bartender uniform saunters up to Izaya aggressively. The two men have a brief exchange, and when Shizuo gives his name Mikado recognizes he is another person Masaomi told him to never cross. Izaya takes out his knife, prepared for a fight when Hiroshi and a group of gangsters surround them. When they see Shizuo, however, they recognize him by his outfit and panic. One of them loses control and hits him in the head with a baseball bat, leading Shizuo to attack all the gangsters, and in the chaos, Izaya bids him goodbye and runs off. Shizuo throws a vending machine after him, but Simon jumps from where he was delivering sushi on the top floor of a nearby building and stops the machine. Mikado grabs Anri's hand and the two run from the scene to a park. Anri leaves, and Mikado watches as Celty drives by.
Elsewhere, Seiji finds the girl with the scar on her neck, proclaiming to have found his love. Later that night, Shizuo talks with Celty, wondering why Izaya was in Ikebukuro. Izaya is seen skipping around the city while reading a message on his cell phone, excited about something. Simon is still advertising sushi fliers in front of Russian Sushi, though he sports a bruised and beaten face, courtesy of Shizuo.
Setton and Kanra tell TarouTanaka that they are both familiar with the Dollars, but warn him to stay away from them. Later, Kanra says the Dollars were behind something, but TarouTanaka assures him that he was there and the rumors are false. However, Kanra was talking about a mugging elsewhere and warns TarouTanaka to stay away from the Dollars as well.
- To episode 1, when Masaomi warns Mikado to stay away from Izaya Orihara and Shizuo Heiwajima
- When Simon is narrating the episode, his accent is American instead of Russian.
- "Flame Haze" is is a reference to Shakugan no Shana.
- Erika's quote "Pipiru piru piru" is from Bokusatsu Tenshi Dokuro-chan.
- Walker mentions Suzuhito Yasuda, artist of Durarara!!, (referring to him as "Suzie") is having a book signing. Walker carries the first volume of Yasuda's manga series Yozakura Quartet.
- There are many posters referring to the series Baccano! and Hell Girl.
Simon: "It's a city overflowing with strangers. They all come here looking for something, and they come to the city hoping to change something."
Simon: "Now and then, the city will give you a gift. These little presents contain big miracles. The very adventure you seek is now there before you, creating a host of new possibilities, and sometimes, the adventure never comes."