Durarara!!: Koukinzoku-hen (2013)

Blurb:
The serial slashings in Ikebukuro have come to an end, and Anri is steadily recovering from her injuries. But life is far from "back to normal" for Kida. Enraged at the random violence that has shattered the peace of his neighborhood, Kida and his middle school crew, the Yellow Scarves, reunite to address the rise of organized gangs in town-the Dollars, the followers of Saika, and now the Yellow Scarves. When all is said and done, who will hold the power on the streets of Ikebukuro?

Source: www.anisearch.com/manga/13285