In the year 2138, virtual reality gaming is booming. YGGDRASIL, a popular online game which is quietly shut down one day.
However, one player named Momonga decides not to log out. As the game shuts down, Momonga is then transformed into his avatar, a skeleton wizard and becomes "the most powerful magic caster in the world."
As the world continues to change, with non-player characters (NPCs) beginning to feel emotion. Momonga decides on his course of action: Having no parents, friends, or place in society, this ordinary young man, Momonga decides to conquer the new world the game has become.