Koaru Karasuma is a vet and the owner of Ginsei, but he didn't know that Ginsei was a Wild Half until almost the end of the series.

Careless, very much in love with his dog, saying that he's the best of dog in the world. Like animals, and is very serious when at the right situation, but that's hard to come by.

One thing to note is that he has silver eyes under those glasses. When he was young, he had a car accident and had been in a terrible state. The doctors claimed that he would lose his eyesight. That night, Ginsei appeared in his dream (That's what he said!) and replaced his eyesight with the boy's.

So, he is able to see colours of feelings, but only when they are very strong.