Hey furs, I figured out what the species really is thanks to the Radywolf book I received today!
Kohaku, nickname is Senpai now, is actually an Oinu Flower. They're basically a Cat, but have human- childlike anatomy/actions, are nocturnal, and their ancestors used to be from the water. That's where I feel Kohaku has Dragon-like features- horns, forked tongue, sharp teeth, and can swim, unlike his cat features- Nocturnal, eyes adjust to light, and Kohaku is the type to sit indoors and watch the well-known "Cat T.V."

-Species owned by Rufen/Radywolf
-Character owned by me !