Merfolk

Merfolk (Japanese Name) are one of the Races of the world. They can also be called Mermaids and Mermen.

Information
Not much is known about the Merfolk besides what was mentioned in Volume 3 of the Light Novels. They resided in Lake Sis / Lake Shisu though were driven out of their homes due to a 'Growing Horde of Amphibious Monsters' which made then seek protection.