The Strongest Devil Becomes A Rookie

The Strongest Devil Becomes A Rookie summary:

Amidst the epic clash between the imperial-level boss and the elite players, a legion of monsters perished, leaving heaps of bodies, ultimately vanquished in a final act of sacrificial explosions. However, to everyone's astonishment, the Supreme Boss is reborn seven years prior, but this time, as a clumsy yet charming rookie, with only modest abilities.