I Slaughtered the Demon Wearing the Duke's Face

Julian, the frail son of the Iron Sword Duke, is constantly bullied by his arrogant brother. After being summoned by a Goddess, he awakens as a rare natural mage with holy angelic powers. Enrolling in a magic academy, Julian quickly proves his strength. When a demonic conspiracy threatens the empire and claims his family, Julian must embrace his destiny, wield his holy sword, and defeat the Lord of Illusions to save the world.