Momonga is the last online member of his game as it is being shut down. He wakes to find himself still in the game, but in a new persona.

Momonga explores the new world he is in, and makes plans with his guardians over how to handle the situation.

Momonga sees that Carne village is under siege by invading forces, and goes to rescue them.

Momonga defeats the Sunlight Scripture that was invading Carne, and launches a campaign to take over the world as Ainz Ooal Gown.

Ainz and his battle maid Narbeal take on aliases of Momon and Nabe, respectively, and join an adventurer's guild to learn more about the world.

Momon and Nabe team up with a group of adventurers called the Swords of Darkness on an adventure.

Momon encounters a fearsome beast known as the Wise King of the Forest - which he finds is a giant hamster.

Momon and Nabe find that their friends were slain by a psychopath and sorcerer, and track the killers down.

Momon and Nabe decimate Clementine and Khaljit.

Ainz's subordinate, the vampire Shalltear Bloodfallen, comes under an enemy's possession and Ainz must make a plan fast to rescue her.

Momonga does damage control at the guild while he assesses the reason for Shalltear's revolt. Coming to the conclusion that she is under an incurable status effect, Momonga goes to the treasury to retrieve some of the powerful weapons of Nazarick.

Though Shalltear's skill set puts Momonga at a complete disadvantage, he steps forward into battle. He gave various world items to his guardians to ensure the safety of Nazarick in his absence. Now, all that is left is a battle of life and death!

Momonga reminds Shalltear that he is the master of Nazarick and that his name carries the weight of all the supreme beings of Ains Ooal Gown. After the battle comes to a close, Momonga quickly takes action to strengthen the defenses of Nazarick.