Sunagawa is a city located in Sorachi Subprefecture, Hokkaido, Japan. As of August 2024, the city has an estimated population of 15,340 and …Sunagawa is a city located in Sorachi Subprefecture, Hokkaido, Japan. As of August 2024, the city has an estimated population of 15,340 and a population density of 190 people per km². The total area is 78.69 km².