Sage

The Sage is a man knowledgeable on magic who works under Flare.

Volume 1
The Sage is present when Keyaru heals Kureha, and while Flare immediately dismisses Keyaru's usefulness upon seeing him in pain, The Sage counters her by explaining potency of Keyaru's healing abilities. He is then given permission to do whatever experiments he wishes on Keyaru, including the use of drugs, to make full use of his healing.

Sabio