Momonga is an ordinary salaryman who spends his spare time playing Yggdrasil, a DMMO-RPG (Dive Massively Multiplayer Online Role-Playing Game) famous throughout Japan for its vast world and unlimited customization options. Unfortunately, all good things must come to an end, and Yggdrasil's servers shut down in the year 2138. Hoping to witness the game’s final moments, Momonga, the leader of the guild Ainz Ooal Gown, logs in for the last time and makes his way to the guild’s headquarters. After reminiscing about his comrades and past adventures, Momonga prepares for the server to automatically log him out as the clock strikes midnight. However, he is not forcefully booted out of the game. Instead, he finds himself in a new world—now trapped in the body of his avatar, where non-player characters are aware of their feelings. With no other options left, Momonga takes on the name of his guild in hopes that other players would recognize Ainz Ooal Gown. Determined to make sense of the bizarre situation, Momonga embarks on a journey to unravel the mysteries hidden in this uncharted world.