SHINMAI NECROMANCER, MAOU WO SOSEI SURU

Shinmai Necromancer, Maou wo Sosei suru summary:

"O spirit destined to be mine, rise once more from the realm of the dead!"
In the depths of an extravagant tomb, Alice, a novice necromancer, channeled her mana into an ancient coffin as she cast her spell. Dust scattered through the air, and a wave of overwhelming mana surged, leaving her breathless. But what emerged was not the mindless undead she had expected—it was a handsome young man, casually perched atop the coffin, his piercing gaze meeting hers.
With a bright, disarming smile, he introduced himself—but Alice soon realized the truth: this was no ordinary man. He was the legendary figure who, centuries ago, had plunged the world into chaos and terror... the Demon King himself.