[2] In 1884 the mine was privatized, and sold to the Fujita-gumi, which later became Dowa Holdings, one of the largest non-ferrous metals producers in Japan.

[3] Following 1901, improvements in smelting technology enabled the company to exploit its large deposits of “black ore” (a mixture of copper, zinc and lead).

In order to attract workers to the remote location, the company built much of the local infrastructure, including apartments, a hospital, theatre, as well as a railroad to connect the town to the Ou Main Line railway at Ōdate.

[4] However, local complains about air and water pollution from the smelter increased dramatically in the 1910s and 1920s, as was the case at the Ashio Copper Mine.

The Meiji period Kosaka Mine Headquarters and Korakukan kabuki theatre have been designated Important Cultural Property in 2002.