In the year 2138, virtual reality gaming is booming. Yggdrasil, a popular online game is quietly shut down one day. However, one player named Momonga decides to not log out. Momonga is then transformed into the image of a skeleton as "the most powerful wizard." The world continues to change, with non-player characters (NPCs) beginning to feel emotion. 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.

30,000 Japanese players trapped in MMORPG, unable to log out. Veteran gamer Shiroe leads exploration of this new reality, negotiating with NPCs to bring order to the virtual city of Akihabara.