[3] The shape of Sado Island resembles the kanji character for ‘work’ (工) in Japanese or the letter ‘S’.

[4] The Kosado range has a relatively flatter terrain with Satsuma orange and tea trees growing there.

However, the Aikawa area on the northwestern side of the Ōsado range are affected by the monsoon blowing from the northwest and the temperature is higher.

When the low air pressure and typhoons pass through the Sea of Japan, Sado Island often suffers from Foehn wind, raising the temperature sharply.

Located at the junction of the warm and cold current, Sado City enjoys diverse plants and rich aquatic resources.

It is thought that the area rose to its current shape, with the Osado Mountains and Kosado Hills sandwiching the Kuninaka Plain.

Thousands of ruins discovered in the Kanai area included stoneware and hunting equipment from the late Yayoi period.

In 1601, miners discovered veins of gold and silver in the Aikawa Tsuruko Ginzan, which became the Sado Mine.

In 1603 (Keichō 8), Tokugawa Ieyasu classified Sado Island as a territory of the Bakufu immediately after his victory at the Battle of Sekigahara.

Its output reached 41 tons by the Bakumatsu period in the mid-19th century, and it played an important role in the financing of the Shogunate.

After the middle of the Edo period, the quantity began to decrease, but output rose to the highest level ever, at 400 kg a year, thanks to the introduction of advanced excavation technology during the Meiji era in the late 19th century.

Japan, under the guidance of Japanese politician Kōko Katō [ja] and Prime Minister Fumio Kishida, went back on its word and created a museum denying that forced labor occurred on Hashima.

[26][29][30] However, on 27 July 2024, the UNESCO committee unanimously decided to register the Sado Island Gold Mines as a cultural heritage site.

[33] The Japanese government established an exhibit about the harsh working conditions, and promised to hold an annual memorial.

Additionally, a representative for the Japanese government told the committee that Japan would make efforts to "comprehensively address the whole history of the Sado Island Gold Mines" in consultation with South Korea.

[34] South Korean President Yoon Suk Yeol's friendlier position to Japan has been analyzed in the context of the approval.