Ainz Ooal Gown was once Satoru Suzuki, an overworked salaryman with no family and few friends, who played YGGDRASIL as the skeletal overlord Momonga. He is the guild master of Ainz Ooal Gown, the last of its members to remain, and the ruler of the Great Tomb of Nazarick. In the New World he is the Sorcerer King, and he also walks among adventurers as Momon, a dark warrior in black plate. He is cautious, calculating, and a hoarder of items. Since becoming undead, strong emotions in him are cut off into calm, cold thought, though milder feelings remain.
Early in YGGDRASIL, player-killers hunted him for his heteromorphic form. He nearly quit until Touch Me rescued him, and the two founded the clan Nine's Own Goal with seven others.
Touch Me later proposed forming a guild and named Momonga its leader. Nishikienrai located the Great Tomb of Nazarick, and the guild conquered it and won the Throne of Kings.
Over the years the members built the Staff of Ainz Ooal Gown and created their NPCs. Nearly all of them eventually quit, leaving their gear with him. He created Pandora's Actor, made the Avataras in his friends' likenesses, and earned the gold to maintain Nazarick alone.
On the last night of the game, Herohero logged out for good. Alone in the throne room, Momonga found Albedo holding a World Item and rewrote her settings so that she loved him.
The servers never shut down, and Nazarick's servants began to think and speak. He sent Sebas to scout the surface, gathered the Floor Guardians on the sixth floor, and tested his magic with Aura and Mare. Every Guardian swore absolute loyalty.
Through a Mirror of Remote Viewing he saw a village under attack and remembered how Touch Me once saved him. He saved Enri and Nemu Emmot in Carne Village, raised a Death Knight against the attackers, and met the Warrior Captain Gazef Stronoff. When the Sunlight Scripture came to kill Gazef, he destroyed their summoned angels and the strike team.
He took the name Ainz Ooal Gown and ordered Nazarick to spread it across the world, so that any other player would hear it.
Disguised as the adventurer Momon, with Narberal as Nabe, he entered E-Rantel and began as a copper-rank adventurer. He escorted the apothecary Nfirea Bareare to Carne Village, where Nfirea guessed his identity and promised to keep it secret.
In the Great Forest of Tob he defeated the Wise King of the Forest, a giant hamster, and named her Hamsuke. She became his mount and pet.
When a cabal kidnapped Nfirea and raised undead in E-Rantel's cemetery, Momon killed the warrior Clementine in a duel while Nabe destroyed their leader and two skeletal dragons. The pair rose to mithril rank.
Shalltear then fell under the control of an unknown World Item. His Wish Upon a Star could not break it, so he faced her alone, killed her with Fallen Down, and resurrected her, which freed her. He never learned who was responsible. He distributed World Items among the Guardians, grew far warier of other players, and was raised with Nabe to adamantite rank.
He ordered Cocytus to destroy the lizardmen of the Great Lake. When Cocytus failed, he changed the order to occupation, and Cocytus defeated the lizardman heroes. Ainz resurrected the fallen Zaryusu Shasha, and the tribes submitted.
Sebas rescued a girl named Tuare, and Ainz tested his loyalty with Pandora's Actor, then promised her protection. When the criminal syndicate Eight Fingers took her, he had it destroyed.
As Momon he drove Demiurge, in the guise of the demon lord Jaldabaoth, from the Royal Capital, and the Kingdom hailed him a hero.
Afterward he learned that the Guardians meant to conquer the world, and he went along with it. He gained the allegiance of the Empire's wizard Fluder Paradyne and destroyed the worker party Foresight when it invaded Nazarick. He had Aura and Mare demand an apology from the Empire, and he put Albedo in charge of a secret unit to search for his lost guildmates.
In the Great Forest of Tob he killed the Giant of the East and gained the loyalty of the Demon Snake of the West. He raised an undead army from the giant's followers and used it in an attack on Carne Village. He later hosted Enri and Nfirea for dinner in Nazarick.
Emperor Jircniv apologized and proposed an alliance. At Cocytus's suggestion, Ainz crowned himself Sorcerer King of a new nation.
At Katze Plains he cast Iä Shub-Niggurath, summoning five Dark Young that destroyed the Kingdom's left wing and sent the Empire's own soldiers running. He then fought Gazef, stopped time, and killed him, and the Kingdom ceded E-Rantel.
He made E-Rantel the capital and moved into the former mayor's residence. He remade the Adventurers Guild into an exploring guild, with Mare's underground labyrinth to train recruits, and he sent Albedo to the Kingdom as a delegate.
In Arwintar he met the merchant Osk, took an interest in dwarven runes, and defeated the Martial Lord Go Gin in the Grand Arena, then revived him. By chance he spoiled Jircniv's secret talks with the Theocracy, and the Emperor offered to make the Empire his vassal.
He traveled to the Dwarf Kingdom with Aura and Shalltear, negotiated trade deals, and drove the Quagoa and Frost Dragons from the old capital of Feo Berkana. Both swore loyalty to him.
Envoys from the Roble Holy Kingdom asked for Momon against Jaldabaoth, who now led a demi-human army. Ainz refused for the sake of order in E-Rantel, then met them in secret and named his terms, which included control over Jaldabaoth's demon maids. He promised to come himself.
In the Holy Kingdom he lent a bow and armor to the squire Neia Baraja, killed the demi-human generals Nasrene, Vijar, and Halisha at Loyts, and revived Neia after she fell in battle.
With Demiurge he staged a duel in which he seemed to fall to Jaldabaoth, testing how Nazarick would respond to his death. He was thought dead. In truth he went into the Abelion Hills, freed the demi-humans there, and allied with them.
He returned for the final battle and defeated Jaldabaoth using a nuclear blast spell, and the demi-human alliance scattered. Neia refused his offer to revive her parents and chose to stay and restore her country.
He rules the Sorcerer Kingdom from E-Rantel. The Empire is his vassal, Re-Estize is crippled, and the dwarves, lizardmen, and Holy Kingdom are tied to him by trade, fear, or debt.
Momon remains the Kingdom's celebrated adamantite adventurer.
He has found no other player and no longer expects his friends to return. The one who controlled Shalltear is still unknown. His main aim is now the happiness of Nazarick's inhabitants.