Death and Thunder

With the official end of the game he and his friends had spent the better part of a decade playing and progressing in upon him, Momonga decides to spend its last moments within the grand tomb he and his friends build in Nazarick. As the servers shut down, however, he is not logged off, rather seemingly is in the body of his skeletal Overlord avatar, now left with in a new world with Nazarick and all of its powerful NPCs. He is not alone however, as one of the 42 members of the guild Ainz Ooal Gown remained with him in those final moments, a player of the slime race, Rimuru Tempest. Now left with just the two of them and their guild's base in this new world, there's nothing left to stop their ambition.