Azad

Azad is an antagonist (currently he isn't) who was a double-agent, pretending to work for Kimun Kamui and Lumineis at same time, with the evil intent of solving their "war problems". Back in time he lived in a village with his family; by far the most precious person in his family was his sister. Later on his life, dragons attacked the village and killed his family; of course, his most mournful loss was his sister. He began to hate dragons as a result and soon loved to see them die.

Now, after losing his powers, he works as a 'Private Detective', keeping an eye on the other world's creatures living in the human world. Recently he's developing a friendly relationship with Saikawa Giorgie, who's interested to help him as his assistant (and put him a butler costume); she seems to remind him his sister.

(Source: Wiki, Official Guidebook)