Virtual reality gaming is thriving in the year 2138. One day, Yggdrasil, a popular online game, is quietly shut down. However, one player, Momonga, refuses to log out. Momonga is subsequently converted into a skeleton in order to become "the most powerful wizard." The environment is changing, and non-player characters (NPCs) are starting to feel emotions. With no parents, friends, or social standing, this ordinary young man Momonga sets out to conquer the game's new universe.