Sado Gold Mine (Sado Kinzan)

The Sado Gold Mine (佐渡金山, Sado Kinzan) is a complex of gold and silver mines located on Sado Island in the Sea of Japan, off the coast of Niigata Prefecture. The term encompasses multiple mine sites, with the Aikawa Gold and Silver Mine (相川金銀山) being the most prominent. The mines operated for nearly 400 years before closing on March 31, 1989.

The gold veins at Aikawa were discovered in 1601, and the Tokugawa shogunate quickly established direct control over the mines, making them a crucial source of revenue for the Edo government. During the Edo period, Sado became the largest gold-producing region in Japan, and the island's mining techniques — including sophisticated drainage systems using Archimedean screws — were among the most advanced in the world at the time.

During the Second World War, the mines took on strategic importance as Japan sought to maximize domestic resource extraction. Beginning in February 1939, the Sado Mine began recruiting workers from the Korean Peninsula to compensate for the shortage of Japanese laborers drafted into military service. Figures for the total vary: a figure of 1,519, attributed to the mine's own records, is often cited, while other accounts put the number of Korean workers who came between 1939 and March 1945 at about 1,200, not counting accompanying family members. Korean workers were assigned to the most physically demanding tasks, particularly underground rock drilling (削岩), and faced discriminatory treatment compared to Japanese workers. Former conscripted workers testified about brutal conditions, including physical violence by supervisors euphemistically referred to as "ki-ai" (気合, "putting in spirit"). By December 1944, the mine was designated a "managed factory" (管理工場) under the Ministry of Munitions, further intensifying wartime production demands.

The mine closed permanently in 1989 after ore deposits were exhausted. In 1994, the Aikawa mine area was designated a National Historic Site of Japan. Approximately 300 meters of the estimated 400 kilometers of tunnels in the Aikawa Mine have been opened to the public as a museum, featuring mannequins and explanatory dioramas illustrating historical mining techniques.

In July 2024, the "Sado Island Gold Mines" were inscribed as a UNESCO World Heritage Site. The inscription process was deeply contentious: South Korea initially opposed the nomination due to Japan's reluctance to address the wartime forced labor history. Japan ultimately agreed to install exhibits acknowledging harsh working conditions for Korean laborers, but critics have noted that the displays avoid the term "forced labor" (強制労働), instead using bureaucratic language such as "recruitment" (募集), "placement" (斡旋), and "requisition" (徴用). The Aikawa Folk Museum (相川郷土博物館) now includes a permanent exhibition stating that Korean workers experienced "harsh working conditions" (過酷な労働環境) during the war.