In the mountains of Niihama, the former mining town of Tonaru has been nicknamed "Machu Picchu of the East" for its brick and stonework ruins. The town developed alongside the Besshi Copper Mines and had a population of 3,700 at its peak in the early twentieth century. It contained the mine headquarters and various mining facilities, as well as amenities such as schools, a hospital, and a public bath.

After the mines closed in 1973, Tonaru was abandoned and its buildings fell into disrepair. Signs of the town and its mining heritage remain in a collection of ruins including the ore sorting yard, the ore storehouse, and various tunnels and tracks used for transporting the ore.