Whenever his temper isn't agitated (which happens a lot, and very easily), Kouma makes clear moral choices which favor ideals of justice and order, if not peace or mercy. Kouma knows a great deal about human ethical norms, but also recognizes that he goes to school among monsters, and simply adjusts his behaviors to whatever he feels is appropriate. As a member of the Protection Committee and subordinate to Tsukune, he's scaled his behavior back, and can be a reliably good guy whenever he's not pissed off.
Was actually forced into the Protection Committee by Riza Wildman, though he blames Ranma for it. He blames Ranma for a lot of things, actually, as the pigtailed boy has been consistently eclipsing and mocking him since they joined the same club. Although Ranma sees their relationship as a tough-guy "brawls and insults" sort of friendship, the hellhound indisputably sees Ranma as an irritating egomaniac, and puts up with him mainly because Ranma is stronger and outranks him, both factors that hold a lot of sway due to his training and upbringing. Kouma hates his dad and despises being treated as a dog due to his emotional baggage. He also has a crush on Riza Wildman, which he thinks is a secret but everyone else in the school would agree is so well-known that nobody even bothers to bring it up.