Aikawa Onsen Tours and Trips (Niigata Prefecture)

Thunder signals the arrival of winter in Sado and exquisite winter yellowtail
Yellowtails migrate through temperate zones, heading north to Hokkaido in spring, and when the seawater temperature drops in Nov., they begin to move south to warmer waters. Around the time when winter thunder can be heard due to the winter atmospheric pressure pattern, the fat-packed winter yellowtail arrive in the waters off Sado. Tasty, plump yellowtails are landed on Sado Island earlier than anywhere else along the Sea of Japan coast, and the thunder at this time is called "buri okoshi" in Sado. The finest yellowtails, caught in fixed nets and carefully selected with a fat content of over 15%, are shipped under the name "Sado Ichiban Kanburi."

The largest gold and silver mine in Japan (※) that was established as a tenryo by the Edo Shogunate
Nishimikawa Gold Mine, the oldest in Sado, was developed in earnest in the 15th century, with gold being extracted by panning. In the 16th century, the Tsurushi Silver Mine was discovered, and silver was extracted by open-cut mining along with the Niiho Silver Mine. The Aikawa Gold and Silver Mine was further discovered in the early 17th century, and was operated by the shogunate as a tenryo (shrine territory). Large-scale mining proceeded in large tunnels. After the Meiji period, Western-style shafts and rock drills were introduced. After coming under the management of the Imperial family, management was transferred to the private sector. Mining continued at the Aikawa Gold and Silver Mine until the beginning of the Heisei period, producing approximately 78 tons of gold and 2,300 tons of silver.
*Source: Sado City