During the early years of Ainz Ooal Gown, the guild managed to obtain the World-Level item known as ouroboros. Due to his dedication to the guild, the players decide to offer the special item to Momonga, the new guild master of Nazarick, as a gift in order to show their gratitude. However, the players soon realise their mistakes as Momonga, in a moment of panick, accidentally wishes for a unique NPC, Tashimī, who is his character's son. In response to his foolishness, the rest of the guild scold the undead for wasting the item on a useless NPC. Years later, YGGDRASIL is about to end, and Momonga decides to spend his last moments in Nazarick's throne room. However, as the clock strickes midnight, the overlord finds himself in a new world, and his son a powerful entity of unmatched might.