The series is set in modern day Ikebukuro, Japan. The story starts when Mikado Ryūgamine, a young boy who longs for the exciting life of the big city, moves to Ikebukuro at the invitation of his childhood friend Masaomi Kida, who he hasn't seen since he was young, to attend Raira Academy with him. After first meeting Masaomi at the train station, they both set out at night to the streets of Ikebukuro. Masaomi warns him about people he doesn't want to cross in the city: like a violent and superhumanly strong man, Shizuo Heiwajima, an information broker, Izaya Orihara, and a mysterious gang known as "The Dollars." After running into some of the said characters, Mikado witnesses a local legend called the "Black Rider", who rides around Ikebukuro on a black bike that occasionally brays like a horse, and who is also rumored to have no head under it's helmet.

The narrative follows all of the characters equally, showing how their lives intersect, creating a greater plotline from what each character knows about a common incident.