Manga/manhwa about yakuza, mafia or like gangster romance? Can be yaoi or straight. I just...

MAFIA
http://www.mangago.me/read-manga/you_re_my_loveprize_in_viewfinder/
http://www.mangago.me/read-manga/dispar_4u/
http://www.mangago.me/read-manga/yondaime_ooyamato_tatsuyuki/
http://www.mangago.me/read-manga/mitsumei/
http://www.mangago.me/read-manga/saezuru_tori_wa_habatakanai/
http://www.mangago.me/read-manga/burns/
http://www.mangago.me/read-manga/madman_combo/
http://www.mangago.me/read-manga/seduction_against_seduction/
http://www.mangago.me/read-manga/gangsta/ (not yaoi)
http://www.mangago.me/read-manga/gray_lujun_kazekaoru/
http://www.mangago.me/read-manga/totally_captivated_dj_mr_sangchuls_diary/
http://www.mangago.me/read-manga/circle_trap/
http://www.mangago.me/read-manga/legs_which_cannot_walk/?ov8I
http://www.mangago.me/read-manga/kobi_no_kyoujin/
http://www.mangago.me/read-manga/cover_up/
http://www.mangago.me/read-manga/trap_city/ (MUST READ)

Gokusen. The art is kinda outdated, it's a slow burn, and the kisses get blocked, but it's worth it. Awesome series.

Acid Town (very slooow update tho)

BL:
http://www.mangago.me/read-manga/canis/

Not BL:
http://www.mangago.me/read-manga/nightmare_funk/

http://www.mangago.me/read-manga/gangsta/?MHFl

http://www.mangago.me/read-manga/hinamatsuri/?n1r8

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

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

http://www.mangago.me/read-manga/gokusen/
- Badass gangster teacher x popular pretty boy <3
- female lead is op/underdog
- chill/no real drama
- funny
underrated and highly recommended :)