 If you liked
Durarara!!
|
 ...then you might like
DRAMAtical Murder
|
They both have gang issues that are important in the story. The protagonists pertain at different gangs that compete with each other with the difference that Durarara!! has only one kind of gang while DRAMAtical Murder has Rhyme and Rib.
In both shows the gang leaders are males and people who knows each other closely.