is a city located in Yamaguchi Prefecture, Japan. As of May 1, 2016, the city has an estimated population of 25,857 and a population density of 54.70 persons per km2. The total area is 472.71 km2. History The city was founded on March 31, 1954 by a merger of municipalities that departed from Mine District (Mine-gun). On March 21, 2008, Mine absorbed the rest of Mine District, which consisted of towns Mitō and Shūhō, while the newly merged city retained the name, Mine. Geography Climate Mine has a humid subtropical climate (Köppen climate classification Cfa) with hot summers and cool winters. Precipitation is significant throughout the year, but is much higher in summer than in winter. The average annual temperature in Mine is . The average annual rainfall is with July as the wettest month. The temperatures are highest on average in August, at around , and lowest in January, at around . The highest temperature ever recorded in Mine was on 26 July 2018; the coldest temperature ever recorded was on 3 February 2012. Demographics Per Japanese census data, the population of Mine in 2020 is 23,247 people. Mine has been conducting censuses since 1920. Attractions Akiyoshidai Quasi-National Park, which includes the and Japan's longest cave, the , the latter of which is designated a Special Natural Monument. Akiyoshidai is served by a natural history museum, visitor center, rest house, youth hostel and park headquarters building, and is traversed by a scenic roadway and several walking trails. Events include a fireworks festival in July, a “Karst Walk” in November, and an annual burning off of dry grasses in February called “Yamayaki”. Akiyoshidai Quasi-National Park is situated within the Mine-Akiyoshidai Karst Plateau Geopark. Akiyoshido, . Towards the southern end of Akiyoshidai is the Akiyoshido cave, named by Emperor Hirohito on May 30, 1926 when he was still crown prince. This spacious cave is up to 100 meters wide and has 8.79 kilometers of passages, making it the longest in Japan and one of the longest in Asia. At the present time an approximately one-kilometer-long section of the cave is open to the public as a sightseeing course, with a walkway and bridge system, entering at the cave's lowest point and exiting via an artificial elevator. This portion of the cave is also well decorated with a variety of large and colorful speleothems. Mine-Akiyoshidai Karst Plateau Geopark Geology The plateau consists