Joushou Maou no Yarinaoshi: Ore wa Mada Ichiwari mo Honki wo Dashiteinain daga

500 years after the strongest demon lord was defeated by the heroine Mia, Al, the lowest adventurer, was tricked by the hero (a descendant of the hero Mia) and obtained a cursed sword. However, the sword caused Al to regain all the power and memories of the demon lord. As the reincarnation of the demon lord, Al embarks on a journey to eliminate the rotten heroes.

(Source: Akita Shoten, translated)