Kasai is a city located in Hyōgo Prefecture, Japan. As of 30 April 2022, the city had an estimated population of 42,494 in 18242 households and a population density of 72 persons per km2. The total area of the city is 150.98 square kilometres (58.29 sq mi).

Hyōgo Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Hyōgo Prefecture has a population of 5,469,762 and a geographic area of 8,400 square kilometres. Hyōgo Prefecture borders Kyoto Prefecture to the east, Osaka Prefecture to the southeast, and Okayama and Tottori prefectures to the west.