Sakai (堺市, Sakai-shi) is a city located in Osaka Prefecture, Japan. It has been one of the largest and most important seaports of Japan since the Medieval era.Following the February 2005 annexation of the town of Mihara (from Minamikawachi District), the city has grown further and is now the fourteenth most populous city in Japan, with 833,414 residents as of May 1, 2007.The current city was legally founded on April 1, 1889 according to the laws of Imperial Japan.