hi! this one shot's really good for what you're looking for:
http://www.mangago.zone/read-manga/gokurakugai_sanbandori_no_ken/
http://www.mangago.zone/read-manga/koroshi_ai/
^ I haven't read this yet but I think it fits what you want
and yakuza bl:
http://www.mangago.zone/read-manga/yondaime_ooyamato_tatsuyuki/
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/
http://www.mangago.zone/read-manga/monetary_love/
http://www.mangago.zone/read-manga/a_thousand_cranes/
http://www.mangago.zone/read-manga/trap_city/
http://www.mangago.zone/read-manga/aka_to_kuro_katsura_komachi/
http://www.mangago.zone/read-manga/cover_up/
http://www.mangago.zone/read-manga/legs_which_cannot_walk/?AV7D
http://www.mangago.zone/read-manga/walk_on_water/
http://www.mangago.zone/read-manga/madman_combo/
http://www.mangago.zone/read-manga/burns/
http://www.mangago.zone/read-manga/isekai_yakuza_mofumofu_no_taizaiki/
http://www.mangago.zone/read-manga/eunsuk_jung_gu/?rvvi
http://www.mangago.zone/read-manga/yondaime_ooyamato_tatsuyuki/
http://www.mangago.zone/read-manga/daddy_tastes_like_butter/
http://www.mangago.zone/read-manga/saezuru_tori_wa_habatakanai/
http://www.mangago.zone/read-manga/acid_town/
http://www.mangago.zone/read-manga/your_devotion_is_my_salvation/
I'm looking for yakuza ish mangas like raise wa tanin ga ii and ojou to banken kun. Please recommend if you have any thanks!