The Regressed Sword Saint’s Magic Theory
回帰した剣聖の魔法理論 / The Magic Theory of the Regressed Sword Saint / Kaiki Shita Kensei no Mahou Riron

In a world where humanity fights monsters, warriors must choose between wielding magic and mastering the sword. Oscar takes the path of the sword, training relentlessly from childhood until he reaches its highest rank: Sword Saint. He defeats fearsome monsters and earns the admiration of the people, living a life many would envy. But beneath his success, Oscar keeps a secret: he has always longed to become a mage.