Ordinary Overlord

In the high fantasy world, the legendary 666-year-old undead evil demon god finally gets defeated and killed by the chosen one. At his dying breath, He chants a reincarnation spell that transports his soul to another world. He is later reincarnated as a human on the earth and tries his best to redeem himself in his next life. The only problem is, he still retains his demon god powers from his past life.