The Magic Tower Problematic Child

The master of the white magic tower, Oscar Sage, and their mages have sacrificed everything—including their lives—for the future of mankind. Twenty years have passed, and Oscar Sage opened his eyes to a reflection of himself in the mirror—a level 1 mage who could only use basic spells—and a White Magic Tower currently at risk of being outcast from the League of the Four Towers. Vowing to restore the White Magic Tower to its former glory, the returning tower master Oscar begins his second life.

(Source: Naver Corporation, translated)