Durarara!!

Mikado Ryuugamine moves to Ikebukuro at the urging of an old friend, expecting the bored small-town life he just left to feel quieter against the city's noise. Within an hour he sees the Black Rider — a headless dullahan on a jet-black motorcycle — and within a week he is at the centre of three intersecting Ikebukuro stories: a missing classmate, the colour-coded gangs feuding for the district, and a quiet information broker named Izaya Orihara who curates the chaos for fun. Durarara follows the city through every viewpoint that touches Mikado's, and one or two that don't.