BL with yakuza or any kind of mafia group

http://www.mangago.me/read-manga/cover_up/
http://www.mangago.me/read-manga/yondaime_ooyamato_tatsuyuki/
http://www.mangago.me/read-manga/jealousy_scarlet_beriko/
http://www.mangago.me/read-manga/leopard_hakusho/

Mayday mayday mayday
Cover up
Under the green light

http://www.mangago.me/read-manga/wolf_in_the_house/

wolf in the house! (mafia stuff starts later in the story) it's one of my all-time favorite manhwas, it's very charming, funny, and mature.

http://www.mangago.me/home/mangalist/1099595/