Mifune is the body guard to the little witch Angela.  He is a master of the sword and the rival of Blackstar. His full name is unknown but what we do know is that he can kick some ass.  He has this tragic background story that molded his tough cool guy persona. 

Even if he doesn't know which side is the bad side and which is good he is still a good person at heart protect those who cannot.

He has the philosophy mindset of the sword warrior.  There is two paths in his eyes, The Path of the warrior and the path of the demon and he hates the demon.  

More specifically the star clan as once in his younger days he witness these corrupted assholes killing a bunch of people in their own homes. 

He is willing to die for the last mission he was hired to do in protecting the witch Angela and eventually becomes a teacher at the end of the series realizing that he can use his wisdom for good. 

Oh and also he is such a badass that his style of swords is literally called ''the god of swords''.