The story takes place in the year 2138 when virtual reality gaming is booming. Yggdrasil, a popular online game, is quietly shut down one day. However, the protagonist Momonga decides to not log out, and then gets transformed into a powerful skeletal wizard. The world continues to change, with non-player characters (NPCs) beginning to feel emotions. Having no parents, friends, or place in society, this ordinary young man Momonga strives to take over the new world the game has become.