The Lord-Magear's Apprentice Vol 1

When one mercenary is ordered to defeat the wizard who saved him, he has only one choice: to become a sorcerer’s apprentice! A fantastical manga about fate, loyalty, and magic. From the creator of Darwin's Game! As a child, Gar the mercenary's life was saved by the legendary archmage Kuon. Years later, he joins a knight order tasked with hunting rogue mages—but the mission ends in disaster when a single sorcerer wipes them out with terrifying power. Facing certain death, Gar is rescued once again by Kuon…and somehow ends up becoming his apprentice. Now, a soldier who’s never cast a single spell must learn from one of the greatest mages alive. Can a warrior who’s lived by the sword survive the world of sorcery?

Source: Penguin Random House API