In the flashy and restless streets of Tokyo's downtown Ikebukuro district, 15-year-old student Mikado Ryuugamine arrives wide-eyed and ready to inhale the exciting breath of city life. Up until now, his only insight into urban affairs was through an anonymous online group chat, where he found out about Ikebukuro's renowned legend. It says that a headless biker known only as the Black Rider roams Ikebukuro, executing its own justice against criminals.

But the district's quirks do not end there; Ikebukuro is swarming with so-called color gangs and their ceaseless conflicts. Among them, a colorless gang known as the Dollars is most noteworthy, as its founder, members, and numbers are all unknown. With odd cliques at every turn and uncanny tales coming to life, humans seem to mix with the supernatural, and Mikado soon dives into the deep sea of Ikebukuro's myths, deceits, and carefully planned out crises—a dangerous world, but possibly one where he belongs.