is a city
located in Iwate Prefecture
The city was founded on February 20, 2006, as a result of the merger between the cities of Esashi and Mizusawa and the municipalities of Maesawa, Isawa and Koromogawa from Isawa District.
The old province of Mutsu, in which modern Ōshū is located, was also known as Ōshū.
The ruins of Iwayadō Castle are located in Ōshū.