The Demon Sword Master of Excalibur Academy - S01

The war against evil is almost over, with only the Undead King Leonis Death Magnus left among the Dark Lords. Knowing he can't win alone, Leonis seals himself underground, planning to reincarnate a thousand years later and raise his demon army anew. But a millennium changes everything. The world has forgotten the great war that once defeated Leonis, and now humanity faces a different enemy-the monstrous Voids. Magic has faded, replaced by enchanted devices, and warriors wielding Holy Swords train at Excalibur Academy to fight the Voids. Reborn as a ten-year-old boy, Leonis is discovered by Riselia Ray Crystalia, a kind-hearted girl who mistakes him for an amnesiac. She takes him in and enrolls him at the academy. Though Leonis still dreams of world domination, he first must adapt to a world utterly unlike the one he once ruled.