Paint the City Red
From Shousetsu Bang*Bang Wiki
Paint the City Red is a story written by Mikami Ren. It ran in Issue 41 at http://s2b2.livejournal.com/238447.html, and is mirrored at http://www.shousetsubangbang.com/mirror/paint-the-city-red/.
Summary
From isis.dreamwidth.org: "Several rival gangs control the city, and the bosses of two of them have frequent hatesex."