4-koma gag comedy spin-off of the Overlord series. A compilation of non-cannon short stories, that revolve around the interactions between the members of the Great Tomb of Nazarick.

(Source: MU)

The story begins with Yggdrasil, a popular online game which is quietly shut down one day. However, the protagonist Momonga decides to not log out. Momonga is then transformed into the image of a skeleton as "the most powerful wizard." The world continues to change, with non-player characters (NPCs) begining to feel emotion. Having no parents, friends, or place in society, this ordinary young man Momonga then strives to take over the new world the game has become.

(Source: ANN)