Guy Crimson  

Guy was summoned to the world by a human as an Arch Demon and was tasked with destroying a nation the human was at war with. He followed that up by destroying the humans nation as well. This earned him his name. An unpleasant-sounding name, like the shrieks of the doomed and desperate as he crushed them. After being named he realized that he had awoken as a True Demon Lord.