Known for his short temper, Shizuo Heiwajima sends a whole biker gang from Saitama to the hospital. Their leader, the strong and handsome womanizer Chikage Rokujou, comes to Ikebukuro to settle the score. However, Shizuo is not his only target; he and his gang intend to also take revenge on the Dollars, who have apparently been wreaking havoc in Saitama.

While Masaomi Kida is gone, Mikado Ryuugamine runs into an unusual problem. His new junior, Aoba Kuronuma, effortlessly finds out about the Dollars' leader and insists on befriending Mikado. Although Mikado tries to distance himself from the Dollars following the advice of an anonymous user—who he assumes is Kida—their online chat's newest member shares unsettling stories of the gang being violent, which makes it difficult to ignore.

Meanwhile, Celty Sturluson goes on a job for yakuza member Haruya Shiki. In her absence, Shizuo is attacked by a young girl who refuses to explain the reason behind it. As Shinra Kishitani tries to help, a mysterious Russian pair shows up with but one goal: to kidnap the strange girl.