Osaka is a designated city in the Kansai region of Japan. It is the capital city of Osaka Prefecture and the largest component of the Keihanshin Metropolitan Area, the second largest metropolitan area in Japan and among the largest in the world with nearly 19 million inhabitants. Situated at the mouth of the Yodo River on Osaka Bay, Osaka is Japan's second largest city by the daytime population after the Tokyo 23 wards, and serves as a major economic hub.