Seihin Of Hikari Secret Lands

In Ryukyu, people are prohibited from leaving the country. It's a place secluded from the rest of the world. However, Nagishima found himself in a government program due to the massive debt of his family. He undergoes training and is sent to an unfamiliar country named Atarashī Kōya where he discovers it's inhabitants are all monsters called Seihin. He is then tasked with mapping the region and documenting it's people and resources.