Sapporo is the fifth largest city of Japan by population, and the largest city on the northern Japanese island of Hokkaido. It is the capital city of Hokkaido Prefecture and Ishikari Subprefecture. It is an ordinance-designated city. Located in the southwestern part of Hokkaido, Sapporo lies within the alluvial fan of the Toyohira River, a tributary stream of the Ishikari River.