Sado Island, located in the Sea of Japan under Niigata Prefecture's jurisdiction, is the second largest island in Japan after Okinawa. With a population of around 55,000, this island boasts diverse topography, including the Ōsado and Kosado mountain ranges and the Kakakura plain. Known for its milder winters and cooler summers compared to mainland Niigata, Sado Island offers a unique blend of natural beauty and rich history, making it a popular destination for tourists and nature enthusiasts alike.