On the day before the MMORPG known as "Yggdrasil" is shut down, guild leader Momonga waits alone in an underground graveyard for his teammates.
Momonga is perplexed after finding himself unable to log out from "Yggdrasil," and the humanlike actions of the NPCs are creeping him out.
Momonga finds a human village called Carne being attacked by a group of knights and decides to fight back.
Carne’s attackers are a special forces group from the Slane Theocracy. Their aim is to assassinate the warrior chief Gazef.
Momonga/Ainz’s next stop is the fortress citadel of E-Rantel. He changes his name to Momon and joins a guild of adventurers to improve his status.
Momon and the Swords of Darkness, a team of adventurers, head to Carne. The members are unable to disguise their surprise at Momon’s combat skills.
The team are surrounded by a group of armed goblins just before arriving at Carne, and find themselves saved by a young girl called Enri.
Momon returns safely to E-Rantel, having improved his status as an adventurer. Meanwhile a showdown with Clementine awaits Nfirea.
Khajiit continues the rites required to turn E-Rantel into a city of the dead. Momon challenges Clementine, who boasts of his great strength.
Momon/Ainz has ordered the vampire girl Shalltear to hunt humans with special abilities, but in the midst of his mission she loses control of herself.
Ainz is bewildered after being suddenly betrayed by Shalltear. The adventurers guild reports more sightings of vampires.
Ainz decides to battle with Shalltear alone and begins to prepare. Demiurge attempts to return to his master.
Ainz attempts to end Shalltear with instant kill magic, but it has no effect. He reveals everything to Shalltear, who is certain of her own victory.
After dealing with Shalltear, controlled by a mysterious enemy, Ainz decides to raise his guard and gather information about the new world.
After the threat of the messenger sent by Ainz, Zaryusu goes in search of help in the other villages of the lizardmen to prepare for war.
After bringing all five tribes together, it is now time for Zaryusu to face the undead army.
The army of the undead sent by Ainz has been defeated. How will the supreme lord react to the news?
The duel between Cocytus and the lizardmen will decide the fate of the village.
At Re-Estize, the eponymous capital of the kingdom, things start to move. Sebas saves a girl, unleashing the anger of the Eight Fingers.
The fields of black dust have been burned, but the capital is still in the hands of the Eight Fingers, while the Blue Roses prepare to fight them.
After informing members of the Blue Roses of the impending attack, Climb meets Sebas on the streets of the capital and asks him to train him.
Sebas, Brain and Climb launch an attack on the clandestine brothel, but waiting for them they find Succulent, a member of the Six Arms.
Ainz reaches the capital to test the loyalty of Sebas. Meanwhile, Princess Renner moves to win the marquis's support.
The operation begins to arrest the members of Eight Fingers, but in one of the buildings the adventurers run into some members of Nazarick.
Ainz finally confronts Jaldabaoth, forcing him to reveal his goal. And so the adventurers prepare for the decisive battle against the demons.
Humans face the demons that have invaded the capital. Evileye and Narberal accompany Ainz in the battle against the demon king, Jaldabaoth.