Sado Island

Sado Island (佐渡島) is an island located in the eastern part of the Sea of Japan, under the jurisdiction of Sado City, Niigata Prefecture, Japan, with a coastline of 262.7 km. In October 2017, Sado Island had a population of 55,212 people. Sado Island covers an area of 854.76 km2, and is the second largest island after Okinawa Island outside of the four main islands of Japan, excluding the disputed Southern Kurils. The shortest distance between Sado Island and Honshu is 32 km. The highest peak on Sado Island is Mount Kinpoku, with an elevation of 1,172 m.

According to the international consensus, during World War II, the island was the site of forced labor. Around 1,500 Korean laborers were conscripted to work in difficult conditions in mines on the island. The Japanese government and some Japanese scholars deny that they were forced to work. In 2022, Japan filed to add the island to the UNESCO World Heritage Site list, which sparked international and domestic criticism.

Geography
The shape of Sado Island resembles the kanji character for ‘work’ (工) in Japanese or the letter ‘S’. The topography of the island can be roughly divided into three parts, the Ōsado range in the north, the Kosado range in the south, and the Kakakura plain with flat terrain in between. The Ōsado range area is higher in altitude, and the highest peak of Sado Island, Mount Kinpoku (1,172 m above sea level), is also located in this area. The coastline on the north side of Mount Sado is steep, and is a famous tourist spot, among which the Senkaku Bay is the most famous. The Kosado range has a relatively flatter terrain with Satsuma orange and tea trees growing there. Its highest peak is Mount Ōjiyama, with an elevation of 646 m. The Nakakura Plain is a large plain in Japan's outlying islands and is also the agricultural area of Sado Island. On the west side of the Kuninaka Plain is Mano Bay, and on the east side is Ryōtsu Bay. The Kokufugawa River (also reads Konogawa River) flows through the Kuninaka Plain, with a total length of 19 km, and flows into Mano Bay. Its watershed area accounts for 20% of Sado Island. Lake Kamo, the largest lake in Niigata Prefecture, is located at the eastern end of the Kuninaka Plain. Lake Kamo was originally a freshwater lake, and later turned into a lagoon after an opening built to the Sea of Japan. Oyster breeding flourishes in the lake. Part of Sado Island belongs to the Sado-Yahiko-Yoneyama Quasi-National Park.

Weather and climate
Affected by the warm Black Current that passes through the Sado waters, the winter in Sado Island is warmer than that in Niigata Prefecture and with less snow. In summer, due to the influence of ocean, the temperature difference between day and night is smaller than that of Niigata Prefecture, and is cooler than that of Niigata Prefecture. 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. Precipitation on Sado Island is mainly concentrated in the end of the East Asian rainy season and early winter, and there is less precipitation than in Niigata Prefecture. 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.

Flora and fauna
Because it is located at the junction of warm and cold currents, it is extremely rich in vegetation, making it an extremely rare vegetation area on the island where plants unique to both Hokkaido and Okinawa coexist. It is also blessed with a variety of marine products, such as dolphinfish, bonito, and bigfin squid that appear in warm currents, and yellowtail that appears in cold currents.

Due to the hundreds of thousands of years that have passed since it was isolated from Honshu, endemic species such as the Sad hare, Sad mole, and Sad shrew can be seen [15]. Although they are now extinct, there was a population of wild boars that was genetically separated from the population of Honshu for hundreds of thousands of years [16]. The Japanese weasel is said to have been re-introduced after becoming locally extinct.

History
Sado Island was originally connected to Honshu, but it separated from Honshu around 16 million years ago due to changes in the topography due to tectonic deformation and volcanic activity, and around 2 million years ago, the ground began to collapse due to compressive kinetic energy in the ocean floor. It is thought that the area rose to its current shape, with the Osado Mountains and Kosado Hills sandwiching the Kuninaka Plain. Uplift continues to this day due to tectonic movements such as earthquakes. With a long history, Sado Island has been inhabited by humans for 10,000 years. Thousands of ruins discovered in the Kanai area included stoneware and hunting equipment from the late Yayoi period. There are also records of Sado in the Kojiki and Nihongi. After the Taika Reform, the central government established the Sado Province on the island, and the local population began to emigrate to Sado Island. At the same time, Sado Island has also become the place where losers of political conflicts or dissidents were exiled. Emperor Juntoku, Nichiren and other people had been exiled to Sado. After the Kamakura period, the Honma clan was appointed as the Shugodai. After 1589 ( Tenshō 17), Uesugi Kagekatsu invaded Sado Island, after which Sado Island was dominated by the Uesugi clan.

In 1601, the miners discovered the gold and silver veins in the Aikawa Tsuruko Ginzan, which is the Sado Mine, for which the status of Sado Island made a great leap. In 1603 (Keichō 8), Tokugawa Ieyasu classified Sado Island as a territory of Bakufu immediately after the victory of the Battle of Sekigahara. Thereafter, Sado Mine developed into the largest gold mine in Japan; the gold output reached 41 tons by Bakumatsu, and played an important role in the finance of the Shogunate. After the middle of the Edo period, the quantity began to decrease. However, the output returned to the highest level ever of 400 kg per year, thanks to the introduction of advanced excavation technology in the Meiji era. In 1989, Sado Gold Mine closed. In nearly 400 years of mining history, it produced 78 tons of gold and 2,300 tons of silver.

After the Abolition of the han system, the Japanese government established Sado Prefecture on Sado Island (later renamed as Aikawa Prefecture). In 1876, Aikawa Prefecture was incorporated into Niigata Prefecture. In 2004, 10 cities, towns and villages on Sado Island merged into Sado City.

Forced labor
According to international consensus, Sado Island was the site of forced labor during World War II, when around 1,500 Koreans were conscripted and forced to work in the mines on the island. The Japanese government, some Japanese scholars, and a minority of international scholars oppose this claim. Koreans are even mentioned in an exhibit in one of the mines, but there is no implication that they were forced to work there.

In 2022, this became the subject of a diplomatic conflict between South Korea and Japan. Japan had previously added Hashima Island, another island where forced labor occurred (which Japan denies despite the international consensus), to the UNESCO World Heritage Site list. However, the nomination was only approved because South Korea and Japan had reached a deal where Japan would acknowledge forced labor in its exhibits. Japan, under the guidance of Japanese politician Kōko Katō and the now Prime Minister Fumio Kishida, went back on its word and created a museum denying that forced labor occurred on Hashima. All other 21 nations of the UNESCO committee agreed that Japan had failed to reach its side of the agreement, but Japan ignored requests to correct the museum. It subsequently filed to have Sado Island added to the list as well, which sparked international and domestic criticism. This request was initially denied due to concerns over how the island's history would be presented. Japan refiled the request on 28 January 2023, with the goal of being added to the list by 2024. Various sources have expressed skepticism on whether the bid will be successful.

Population
In 1960, Sado Island had a population of 113,296. Due to the inconvenience of living on the outlying islands and lack of jobs, Sado Island has experienced a long-term population decline. In October 2017, the population of Sado Island was 55,212. The total fertility rate of Sado Island is about 1.9, which is much higher than the average of Japan and Niigata Prefecture. However, the continuous outflow of population results in the persistent decrease of population.

Culture
Since Sado Island is an important trading base on the Nishimawari naval route from the coast of the Japan Sea to Osaka, the culture is strongly influenced by West Japanese culture like Kinki and Hokuriku. Also, intellectuals and politicians exiled from Kyoto to Sado brought the traditional performance culture of Kyoto, thus the traditional art of Sado Island began to thrive. The Noh Master Zeami Motokiyo was exiled to Sado, resulting in the particular development of Noh culture in Sado. In the Edo period, there were more than 200 Noh stages. Sado still has more than 30 Noh stages, and the number of Noh stages per capita ranks first in Japan. There are also local performing arts such as ‘Ghost Taiko’ on Sado Island.

Sado is also home to the Kodō taiko drumming troupe. Kodō are credited with popularizing modern taiko drumming both in Japan and worldwide. Kodō Village is based in the Ogi subdivision.