The two guys meet and the black haired(?) guy tells the blond guy his name, which is also the name of the person the blond is looking for. They end up working together to do something. The blond tries to get the black haired guy's trust so he could kill him, but the black haired guy is already pretty laid-back and has given the blond guy plenty of opportunities for that.
Suddenly one of the blond's acquaintances meets them and pretends to hold blondy hostage. The buddy tells blondy to shoot the black haired guy because he won't expect it from his partner.
From here, i think blondy is debating whether he should shoot the acquaintance or the black haired guy. In the end, the black haired guy shot one of them, I'm not too sure which.
Hopefully this has enough details to find that manga!!
