i remember that the contract killer and the normal guy were friends in high school and eventually met again after the contract killer moved/left school? the art style was pretty unique and i think the killer had long white hair while the other guy had short black hair. white hair guy's attitude was the bubbly yandere kind while black hair guy was serious and quiet.

in the story, the contract killer takes the normal guy to a bar for other criminals and another criminal scares him. the main couple get close really quick and the black hair guy lets white hair guy sleep over. something happens in the relationship and i think they break up. the art was really distinct so i hope anyone else saw it.

nvm found it, OΣG!!! =Oh My God= by Namagomi. the wonders of searching by filtered tags