Kasugayama Castle is a Sengoku period yamashiro-style Japanese castle located in the Nakayashiki neighborhood of the city of Jōetsu, Niigata prefecture. It was the primary fortress of the warlord Uesugi Kenshin, and was originally built and ruled by the Nagao clan. It is listed as one of Japan's Top 100 Castles and the ruins have been protected as a National Historic Site since 1935. The castle and its history were mentioned by Takizawa Bakin, and Yamazaki Yoshishige in Tanki manroku. Kasugayama Castle is regarded as among Japan's Five Greatest Mountain Castles, along with Nanao Castle, Odani Castle, Kannonji Castle and Gassantoda Castle. The castle is unofficially called Hachigamine Castle .

Jōetsu is a city located in Niigata Prefecture, Japan. As of 1 December 2020, the city had an estimated population of 189,430, in 76,461 households with a population density of 190 persons per km2. The total area of the city was 973.81 square kilometres (375.99 sq mi). Jōetsu borders the Sea of Japan and is renowned for its abundance of snow, the annual cherry-blossom festival, sake and Koshihikari rice.