Rebirth of the Demon Lord: the Slave who Conquered Fate

Summary

To fight the monstrous "Outsiders" invading from outer space, the world's strongest Hero and Demon Lord joined forces. However, their alliance was ultimately defeated. In a desperate bid to change history, the Demon Lord, with the help of Hero's secret technique to reverse time and undergo reincarnation.Reborn as a boy who was bullied and enslaved in noble society, the Demon Lord now faces a cruel new reality."Why is a slave so strong?!" "Strong? He's not just stronghe's a monster!!"With his overwhelming strength from his previous life intact, the Demon Lord trains relentlessly to rise to the top and ensure victory this time!