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. Sakai became a designated city in April 2006 giving it a greater measure of self-determination in governmental affairs. It is divided into seven districts.Sakai is known for its keyhole-shaped burial mounds, or kofun, which date from the 5th century. The largest of these, Daisen Kofun, is believed to be the grave of the Emperor Nintoku and is the largest grave in the world by area. Once known for samurai swords, Sakai is now famous for the quality of its kitchen knives; most high-quality Japanese cutlery originates in Sakai, and its production is a major industry in the city.As of August 1, 2011, the city has an estimated population of 842,760 and a population density of 5,600 persons per km². The total area is 149.99 km².