In the year 2126, a Dive Massively Multiplayer Online Role Playing Game or DMMO-RPG called YGGDRASIL was released. It stands out among all other DMMORPG's due to its unusually high ability for the player to interact with the game. After an intense 12-year run, the game servers are about to be shut down. Within the game exist a Guild, Ainz Ooal Gown, once consisting of 41 members and credited as one of the strongest guilds in the game. Now only four of the members remain, the other 37 having quit the game. Of those four only one actually continues to play; his name is Momonga and he remains the guild leader, maintaining their headquarters, the Great Tomb of Nazarick. He invites the remaining guild members, but of those only one appears and only for a short while before leaving. Though Momonga is saddened by this, he accepts the reality that his friends have their real lives to take care of. And so, he stays in the guild alone until the servers shut down.
Upon waking up, Momonga realizes that the game may not have shut down properly as he is still in his avatar form and he cannot seem to use the normal Player function, such as Message, or even quit. Then when the NPC's of Ainz Ooal Gown start talking to him, he decides to take things seriously and find out if anyone from World of 2138 is also in this New World with him. Taking on the name of Ainz Ooal Gown for the sake of his guild, Ainz wanted to send a message to any other players out there facing the same circumstance as he have. Henceforth, he begins exploring the world that is supposedly different from YGGDRASIL. He tries to figure out what has happened while trying to find anyone, or anything, that could help him solve this mystery.