Sakai is a city located in Osaka Prefecture, Japan, on the edge of Osaka Bay at the mouth of the Yamato River. 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, the city grew to the fourteenth most populous city in Japan, with 828,741 residents as of June 1, 2019.
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 wards.