This is an island kingdom, and it is also a magical kingdom. It has experienced thousands of years in the middle of the sea. Several small islands around it are under the jurisdiction of this kingdom. They are all isolated from the mainland. No one from the outside world has arrived here. No one has stepped out of the jurisdiction of this country for thousands of years. However, every ten years, the appearance of this country will be seen by people on the mainland in a mirage, so outsiders named this kingdom the Holy City of the Sea.