Мерлин

Merlin is the uncle of Celia, Tenma's adoptive mother, and is known across the world by the epithet "the Sage." By the time he meets Tenma he had been away from Kukuri Village for some eleven years.

Recognizing the boy's talent, Merlin takes him on as a direct pupil, teaching him magic-power control and magic itself. Tenma comes to call him "Grandpa." Beyond mentoring, Merlin joins the village's defense, unleashing area fire magic on attackers.