Hotsuma is one of the Zweilt guardians, and he can use fire as he likes. He is short tempered and impulsive. He has been friends with Shuusei since childhood. At first he dislikes Yuki, since he thinks that he has the same personality has he had in his previous life (which indicates that maybe he used to be in bad terms with female Yuki), but with time it seems that he will grow somewhat close to him.
Source: Wikipedia