【Designated by the City：Historic Site】Usubariabu

Usubariabu is diagonally across Kanamaraabu (at the northeastern side), which is located about 300 m north from the middle of Farm Road 78 in Nagayama, south of Irabu Island.It is about 35 m deep with the entrance about 2 m wide and 4 m long. Its first stepping point after the entrance is about 14 m below. The cave is about 25 m long from north to south, and 10-15 m wide. From the first stepping point, a tunnel develops 12 m towards the north, and on the western wall of the first stepping point, there is a gravel layer with many pieces of buried human and animal bones. Likewise, on the eastern wall, there is a gravel layer of 4 m in width and 2 m in height, and tridacna shells, turban shells, and human bones can be observed on the surface.
To the south of the first stepping point, there is a cave. The tunnel leads to the second stepping point 18 m below, which is an oval-shape that is 4 m wide and 7 m long.　From Usubariabu, jaw bones and 21 teeth of a child between 8 and 10 years old have been collected.