A man reincarnated as a demon, but because he was the newest, he was the weakest and often abused by the others. He started to feel extensive hatred for them and his humanity was lost. After a decade, there were no demons, so he continued to suffer and his original personality was destroyed. He became a vengeful sadist who only wanted to inflict the pain he'd experienced on others. Soon, he was summoned to the living world of humans, elves and dwarfs, by a pitiful little girl who died soon after but not before entrusting her life and body to him requesting that he kill all the orcish who had destroyed her village. He accepted and became an incarnated lesser demon, much stronger than in the hell he'd been in. He wants to be feared by every living thing in the entire world. So, he resolved to become the world's Master.