Finder Series

Boys love with dark themes and tones, even have a blonde haired black haired pairing. 

The semes are both oppressive and possessive while the uke is whiny and full of resistance ( but not giving a good fight...in different ways). Although Ai no Kusabi is more about the societal/class influence and not as micro as Finder's take on yakuza, there are similarities in terms of the author's perspective on life (Life sucks for Fei Long all the way and same for Gai/Rikki), that it sucks, of course. Ai no Kusabi is a classic for yaoi. The 2012 remake version is slightly more parallel to the novel but the original animation is complete in its own way. See it to check it out. read more 

Slightly less graphic than Enzai. But both present sadomasochistic interactions and rape scenes. Unlike "Enzai", "Finder no Hyouteki" has some romantic undertones.  

In terms of genre, it is all about Boy x Boy. Also, you cannot deny how the art is pretty similar. The only difference you can find is perhaps the context which is different! So if you like one, you may like the other one!  

dealing with underworld organization, rape, and betrayal for both uke sides