Mikado Ryugamine, a young man longing for something unusual to happen in his life, moves to Ikebukuro at the invitation of his childhood friend Masaomi Kida. Arriving in Tokyo for the first time, he begins his new life living alone as a high school student, awed and mesmerized by the new world around him.

It is the Entrance Ceremony at Raira Academy, and the auditorium swells with a varied mix of emotions emitted from the students. Amidst all this is Rio Kamichika: a girl with a notably dark vibe following her.

Masaomi Kida is out about town, fervently trying to pick up girls, while Mikado tags along, feeling a bit confused and bewildered. Various people intermingle throughout Ikebukuro as rumors of the “Dollars” spread.

People throughout the city speak of an urban legend known as the "Headless Rider." A surprising number of people have personally witnessed it speeding down the streets on a jet-black motorbike with no license plate. It is, without a doubt, a mysterious being that can meld simultaneously with the darkness as well as the hustle and bustle of Ikebukuro. But does anyone know the true form of the Headless Rider? One man, Shinra, ponders this mystery while the Headless Rider itself continues to wander the city, in search of the whereabouts of a lone elderly painter.

Mikado, Masaomi, and Anri all enjoy some after-school time, while elsewhere, magazine writer Shuji Niekawa makes little progress in his search to find "the Strongest in Ikebukuro." Everyone has a different opinion: The Headless Rider, the Dollars, Simon, Shizuo Heiwajima, the Yellow Scarves, and the "Slasher." There is no consensus. The Headless Rider confronts a shadowy being with two crimson eyes glowing in the darkness of back alleys of the city one night while, at the same time, a certain chat room is trolled by the user "Saika (Sin Song)".

As of late, an increasing number of people have been going missing in the districts of Ikebukuro and Shibuya. However, those that have gone missing are people that will not be missed much such as fugitives and illegal aliens. And today, once again, a group of illegal aliens living in an abandoned hotel, have fallen victim to some young "man hunting" thugs with metal pipes and knives. They capture the fleeing "merchandise" with much enjoyment, but the question lies: where do they take them? And who will have the nerve to stand up and save these people?