Osaka City, Japan

Osaka is a city in the Kansai region of Japan's main island of Honshu, a designated city under the Local Autonomy Law, the capital city of Osaka Prefecture and also the largest part of the Keihanshin metropolis, which comprises three major cities of Japan, Kyoto, Osaka and Kobe. Located at the mouth of the Yodo River on Osaka Bay, Osaka is Japan's third largest city by population after Tokyo (special wards) and Yokohama.
Keihanshin is the second largest metropolitan area in Japan by population and one of the largest metropolitan areas highly ranked in the world, with nearly 18 million people,and by GDP the second largest area in Japan and the seventh largest area in the world.
Historically the commercial center of Japan, Osaka functions as one of the command centers for the Japanese economy. The ratio between daytime and night time population is 141%, the highest in Japan, highlighting its status as an economic center. Its nighttime population is 2.6 million, the third in the country, but in daytime the population surges to 3.7 million, second only after Tokyo (combining the Special wards of Tokyo, which is not a single incorporated city, for statistical purposes. See the Tokyo article for more information on the definition and makeup of Tokyo.) Osaka used to be referred to as the "nation's kitchen"  in feudal Edo period because it was the centre of trading for rice, creating the first modern futures exchange market in the world.