is a city located in Okayama Prefecture, Japan. As of 2020, the city has an estimated population of 69,343 and a population density of 322 persons per km2. The total area is 211.90 km2. History In the 7th century, Ki Castle was built atop the mountain Kijōyama. Long in ruins, excavation and partial reconstruction began in 1999. The city was founded on March 31, 1954. On March 22, 2005, the villages of Yamate and Kiyone (both from Tsukubo District) were merged into Sōja. Geography Adjacent municipalities Sōja is surrounded by the following cities and towns, all within Okayama Prefecture. Okayama Kurashiki Ibara Takahashi Yakage Kibichūō Rivers Takahashi River Shinpon River Makidani River Mountains Ki castle mountain Mount Fuku Mount Karube Sister cities Sōja has been twinned with Chino, Nagano in Japan since 1984. References External links Cities in Okayama Prefecture