i think one of the best things about kiryu is that he doesnt kill people not because of some bizarre moral code specifically like batman where he believes if he starts that he'll never stop, but because he doesnt think anyone has the right to cut another man's life short even if the victim would be another murderer or a sadistic torturer
he loves to fight, he knows it's what he's best at, but he doesnt want to end a life doing it and i think that's beautiful, he is the epitome of guys being dudes