Help me find this manga

Help me find this manga pls. It was a tragedy kind of psychology bl manga. All I remember is that he was a mercenary or maybe an assassin type of dude. He's got dark hair and a muscular build where he deals with this psychopathic slender dude who killed himself. I feel like the psychopathic dude was being targeted and he tried killing someone else, was it a woman in a mall? I don't know and after that he killed himself I think it was with a knife too. Then there was this panel of the mercenary dude looking hella unkempt but hot like carlos Oliveira. He was holding a gun and got ambushed or maybe they were fighting someone after talking to a subordinate. Then the last chapter is him visiting a woman with a child while the other guy haunts him questioning his morality and whatnot as though he's suffering mentally. I think it was under 10 chapters or 12 chapters.