Beast King Mekongawa

Beast King Mekongawa (獣王メコン川) is a guild member of Ainz Ooal Gown, and regarded as one of the Forty-One Supreme Beings by the NPCs of the Great Tomb of Nazarick.

Background
Other than YGGDRASIL, Beast King Mekongawa also plays another DMMO-RPG called Aberage with Nishikienrai together.

When Beast King Mekongawa heard that Nishikienrai was among the upper ranked players in the game with the title of Violet, he thought about quitting the game. This is because he was only in the Green rank unlike his guild member who is higher in rank than him.

However, Beast King Mekongawa was encouraged by Nishikienrai to not quit the game as his friend was willing to group together with him next time.

Beast King Mekongawa was among the members of the newly created guild, Ainz Ooal Gown, that attacked the Great Tomb of Nazarick.

Main Equipment

 * Ring of Ainz Ooal Gown: It allows the user to freely teleport between every room inside Nazarick. Every member of Ainz Ooal Gown was required to wear this ring.

Nishikienrai
Let alone in YGGDRASIL, it seems apparent that friendship between the two extends to another DMMO-RPG called Aberage. His guild member, Nishikienrai was willing to play Aberage with him when he is in a dire crisis like almost quitting the game.

Quotes

 * (To Nishikienrai): "Ehh?! What did you say? Doesn’t that mean you’re a super top-class player? I’m just a Green. Maybe I should quit Aberage"