Azuma Koshiishi is a Japanese politician of the Democratic Party, a member of the House of Councillors in the Diet, and general secretary of the ruling Democratic Party. A native of Nirasaki, Yamanashi, and graduate of Tsuru University, he was elected to the House of Representatives of Japan in 1990, where he served for two terms until 1996 when he failed to be re-elected. He was elected to the House of Councillors for the first time in 1998.

Nirasaki is a city in Yamanashi Prefecture, Japan. As of 1 October 2020, the city had an estimated population of 28,150 in 12831 households, and a population density of 210 persons per km². The total area is 132.69 square kilometres (51.23 sq mi).