This is an ancient mountain castle that was built in 667 AD. Surrounding a rocky mountain at an altitude of 375 meters, a 2.2 kilometer long stone wall remains. One of the country's special historic sites. There is a shrine in the sea waters and it is assumed that people would worship from inside the sea.
In 1901, a turret was installed, so there are now roads suitable for climbing. The view from here is also good, and it can be seen that it was a place that was a look out point for invaders from the land. Hence, Shimura was never captured.