Mugongeuro Level Up-aneun Mawangnim

Now that the demonic realm and the heavenly realm have called a truce, the human world has returned to an era of peace. Jeon Minchul lives the life of an ordinary college student until the day he comes across an artifact from the war and remembers—in his past life, he was the demon king who brought the world to its knees. Upon recalling these memories, Minchul awakens his old powers, along with some new ones. But can this demon king harness the powers of both good and evil to protect the peace?

(Source: Tapas)