Galuna Island

Galuna Island aka "The Demon Isle" is an island shaped like a crescent moon that is the home of a tribe of friendly Demons. It is said that this island is cursed for the people there is turning into a Demon if the moon show in the night.

History
At some point in time the residents of Galuna Island were placed under a spell that made them turn into humans in the daytime. The spell also affected their memory so they didn't remember they were demons, thus, they thought they were cursed to be demons at night. This led them to believe that the moon was the cause of their curse. At some point, some people didn't change back any more, making them believe that they've lost their souls. They decided to kill everyone who they believed had turned into real demons, afraid that they'd kill the rest of the village's members if they didn't do that. Unable to handle the situation any longer, they've found themselves in, they began to seek help from Guilds to cure them.