Overlord Manga

Overlord manga is based on the light novel series of the same name. It was published by Kadokawa Shoten with illustrator Hugin Miyama and has currently two volumes out and is ongoing. The chapters can be found.

Plot
The story begins with Yggdrasil, a popular online game which is quietly shut down on its last day. Our protagonist Momonga decided to stay until the last moment in his beloved game and wait for the force logout. Unexpectedly, the server did not shut down and Momonga is stuck in his skeleton body and got transferred to another world. "The powerful Overlord" needs now to discover a new world and face the continuous challenges.

Having no parents, friends, or place in society, this ordinary man strives to take over the new world the game has become. (Taken from Mangafox)

Names

 * Impregnable Fortress - Known as Invulnerable Fortress in the Light Novel