Being X is the main antagonist of the Youjo Senki series. It is, in its own words, "God", but Tanya in her first meeting with it labeled it as the devil. Being X is a mysterious being. It claims to be a God, the God of the Bible, the one that gave the 10 commandments to Moses.

However, there are a number of Gods and Archangels overseeing the world(s), which goes against what is postulated in the First Commandment. Its goal appears to be the increase of the number of faithful people in the world.