mafia yaois

http://www.mangago.zone/read-manga/dangerous_convenience_store/

http://www.mangago.zone/read-manga/our_companionship/ this one is shounen ai but i'd say it's a but yaoi. just a tad bit

I’ll pick the best manga I’ve read, gimme 5 minutes

http://www.mangago.zone/read-manga/when_the_yakuza_falls_inlove/

http://www.mangago.zone/read-manga/yondaime_ooyamato_tatsuyuki/

http://www.mangago.zone/read-manga/trap_city/

http://www.mangago.zone/read-manga/a_thousand_cranes/

http://www.mangago.zone/read-manga/madman_combo/

http://www.mangago.zone/read-manga/goriyou_wa_keikakutekini/

http://www.mangago.zone/read-manga/eunsuk_jung_gu/

http://www.mangago.zone/read-manga/mayday_mayday_mayday/

http://www.mangago.zone/read-manga/under_the_green_light/

http://www.mangago.zone/read-manga/park_hanhoo_s_manager/ (shounen ai)

http://www.mangago.zone/home/mangalist/1129188/

Its a new list im gonna add more soon.

This is the first thing I thought of http://www.mangago.zone/read-manga/cover_up/

Long/ serialized manga:
http://www.mangago.zone/read-manga/yondaime_ooyamato_tatsuyuki/
http://www.mangago.zone/read-manga/jealousy_scarlet_beriko/ (sequel/side story)
http://www.mangago.zone/read-manga/bi_no_isu/
(1)
http://www.mangago.zone/read-manga/kobi_no_kyoujin/ (2)
http://www.mangago.zone/read-manga/bi_no_kyoujin_smoke/ (3)
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/
http://www.mangago.zone/read-manga/saezuru_tori_wa_habatakanai/

Manhwa/hua:
http://www.mangago.zone/read-manga/a_thousand_cranes/ Best manhwa about yakuza
Ok I’m sleepy so I won’t add anything more
Take this http://www.mangago.zone/tag/Yakuza/

Uhh, how about "A thousand Cranes"?