is a city located in Ehime Prefecture, Japan. , the city had an estimated population of 35,456 in 17627 households and a population density of 69 persons per km². The total area of the city is . Geography Seiyo is located in southeastern Ehime Prefecture, with Uwa Bay on the Seto Inland Sea to the west, and with the Shikoku Mountainsto the east, with a difference in elevation of 1403 meters. The city area is long from east to west and due to its diverse topography, it was certified as a Japanese Geopark (Shikoku Seiyo Geopark) by the Japan Geoparks Committee on September 24, 2013. Onogahara, which is part of the Shikoku Karst, one of Japan's three major karst landscape, is very beautiful with its green grassland and white limestone. Komatsu is home to Rakan Cave, one of the largest caves in Shikoku, which is open to the public as a show cave with a length of 700 meters. Neighbouring municipalities Ehime Prefecture Ōzu Yawatahama Ikata Uwajima Kumakōgen Uchiko Kihoku Kōchi Prefecture Yusuhara Climate Seiyo has a diverse climate, from the inland mountain plateau (Onogahara), where more than 2 meters of snow accumulates in winter, to the warm coastal area, and the basin with a lot of fog due to the influence of two dams. During the typhoon season, coastal areas are often damaged by high tides and high waves, and mountainous areas are often damaged by landslides caused by heavy rain. The temperature can differ by more than 10 degrees between the coastal area and Onogahara. In general, Seiyo has a Humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light snowfall. The average annual temperature in Seiyo is 15.3 °C. The average annual rainfall is 1663 mm with September as the wettest month. The temperatures are highest on average in January, at around 26.1 °C, and lowest in January, at around 4.7 °C. Demographics Per Japanese census data, the population of Seiyo has been decreased steadily since the 1960s. History The area of Seiyo was part of ancient Iyo Province. During the Edo period, the areaway part of the holdings of Uwajima Domain or its subsidiary Iyo-Yoshida Domain. Following the Meiji restoration, the area was organized into towns and villages within Higashiuwa District and Nishiuwa District in Ehime Prefecture. The city of Seiyo was established on April 1, 2004, from the merger of the