Responses
http://www.mangago.me/read-manga/when_the_yakuza_falls_inlove/
http://www.mangago.me/read-manga/mayday_mayday_mayday/
http://www.mangago.me/read-manga/madman_combo/
http://www.mangago.me/read-manga/deliverance_of_the_counterattack/
http://www.mangago.me/read-manga/legs_which_cannot_walk/?64rz
http://www.mangago.me/read-manga/dear_benjamin/
http://www.mangago.me/read-manga/a_thousand_cranes/
http://www.mangago.me/read-manga/our_companionship/?RXpq
This is the list
http://www.mangago.me/tag/Gangster/
Looking for Mangas with a similar concept to Dangerous convenience store, with a gangster seme