Ikebukuro, a district of Tokyo. A young man named Mikado Ryugamine has moved there from "the sticks", clueless as to how things work in the big city. Reunited with his childhood friend Masaomi Kida for the first time in years, Mikado is shown the way around town as he tries to adapt to the hectic ways of the busy metropolis and discovers its many dark secrets.
Word on the street is that a mysterious motorcyclist with no head called "The Black Rider" (a modernized Dullahan from Celtic Mythology) has been riding about committing acts of vigilante justice in a spectacularly violent fashion.
There's a guy who dresses like a bartender with inhuman strength, a shady Knowledge Broker, a genius Back Alley Doctor, and a conspiracy about a pharmaceutical company involved in human trafficking. Then there's the "Dollars", a mysterious gang whose members and activities are shrouded in secrecy.