Ōsaki is a city located in Miyagi Prefecture, Japan. As of 1 May 2020, the city had an estimated population of 128,763 in 51,567 households, and a population density of 160 persons per km2. The total area of the city is 796.76 square kilometres (307.63 sq mi). Ōsaki is a member of the World Health Organization’s Alliance for Healthy Cities (AFHC).

Miyagi Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. Miyagi Prefecture has a population of 2,265,724 and has a geographic area of 7,282 km2 (2,812 sq mi). Miyagi Prefecture borders Iwate Prefecture to the north, Akita Prefecture to the northwest, Yamagata Prefecture to the west, and Fukushima Prefecture to the south.