Technically not cold-blooded murder. It was justified self defense. The author even frames the weapons the attacker had attempted to use. Of course the misunderstanding is it was murder but potentially we don’t go through that trope.
@yihdego
it's not really self defense to bait someone into fighting you to the death. guy was supposed to tail him, but it's his own fault for fucking up.
the point isn't that ryuki killed the dude, we've seen him absolutely intend to kill people before. the point is that he's got no problem with it. and to freak out koga, ofc.