Ainz Ooal Gown, once called Momonga and now an undead mage, has embraced his role in this unfamiliar realm. While it echoes the beloved VR title Yggdrasil, countless enigmas remain that he plans to solve using his authority as the sovereign of the Great Tomb of Nazarick. Yet after a severe mind‑control incident involving one of his lieutenants, Ainz grows cautious about the looming threats posed by the Slane Theocracy and the potential presence of other Yggdrasil veterans. At the same time, Albedo, Demiurge, and the remaining devoted protectors begin preparations for their next move: Nazarick"s inaugural battle… in the vast continent for all realms and ever beyond.
Overlord II picks up after its prequel, following Ainz Ooal Gown, army of anti‑human guardians and the humans affected by arrival.