Although a magus, he has no connections to the Mage's Association and, rather, is closer to a spellcaster.
Geronimo is a warrior of the Apaches, one of the aboriginal people from the North American continent. Originally owner of a carefree name that meant 「the one who yawns」 in the Apache language, his life completely changed when he was 20 years old. Upon having his wife and children slaughtered by Mexican soldiers, he made a bold speech and carried out a revenge against the Mexican army as a 「warrior」.