Manga where a girl is about to jump off a building and commit suicide before she witnesses a boy dragging a dead body. The boy killed someone and notices her, he walks up the building and plans to kill her too before she says or does something that makes him change him change his mind. (can't remember what she says, maybe something along the lines of you can kill me?) From that point in the story the two kinda work together. The boy kills a lot of people and they end up being chased by the mafia and either the boy or girl can't remember which, ends up locked in a dark mafia room with tea that will make them more thirsty if they drink it. It was kind of a horror, action manga with really hood art and crazy characters. If anyone knows the name of it or any more info please share!

________________
Shoo, Nothing to see here!

Sounds like Kami-sama, Ki-sama o Koroshitai..