The year is 2138. The virtual reality somatosensory online game "YGGDRASIL", which once caused a sensation, is about to be discontinued. Player Momonga is quietly waiting for that moment alone in the Great Underground Tomb of Nazarick, the base where he once prided himself on his companions and glory. However, an abnormal situation occurred unexpectedly: "The end time has passed but he has not logged out." NPCs began to act according to their own will, and not only that, a different world that has never been seen before unfolded outside of Nazarick. In order to find his former companions, Momonga calls himself Ainz Ooal Gown, a guild name, and decides to make a name for himself in another world. Together with his subordinates who swore absolute loyalty, he marched into a new area.