ウェブContents. Osaka Prefecture. Japan. (1 July 2019) Osaka Prefecture (大阪府, Ōsaka-fu, pronounced [oːsaka ɸɯ]) is a prefecture of Japan located in the Kansai region of Honshu. [2] Osaka Prefecture has a population of 8,778,035 (as of 1 April 2022) and has a geographic area of 1,905 square kilometres (736 sq mi ).