The story begins with Yggdrasil, a popular online game which is quietly shut down one day. However, when the protagonist Momonga decides to log out as the server shuts down, he found himself trapped in the world of Yggdrasil as his in game character, a powerful skeletal wizard. The world continues to change, with non-player characters (NPCs) beginning to feel emotion and becoming life-like. Momonga becomes cold and calculating, while having his emotions suppressed, as if he was not an actual human. Having no parents, friends, or place in society, this ordinary young man Momonga then strives to take over the new world the game has become.