From MangaHelpers:

This is a story about teenagers and gangs in Yokohama. Junya, Teru and Makio used to be good friends as children. As they became teenagers, however, Makio joined a gang and seemed to become a completely different person. Now, Makio's, Junya's and Teru's lives are plagued by violence as they try to navigate what once was and what their lives have become. [tethysdust]