Oyumi Domain

 was a Japanese domain of the Edo period, located in Shimōsa Province (modern-day Chiba Prefecture), Japan. The site of the Oyumi "jin'ya" is now under a residential area of the city of Chiba. The domain was ruled through its entire history by the Morikawa clan.
History.
Oyumi Domain was created in February 1627, when Morikawa Shigetoshi, a "hatamoto" in the service of Shōgun Tokugawa Hidetada acquired holdings in Sagami, Kazusa and Shimōsa Provinces with revenues exceeding the 10,000 "koku" necessary to qualify as a "daimyō". He was allowed to build a "jin'ya" on the site of the Sengoku period Oyumi Castle. He later rose to the post of "rōjū", and committed "junshi" on the death of Tokugawa Hidetada. His successors continued to rule Oyumi Domain until the Meiji Restoration.
Holdings at the end of the Edo period.
As with most domains in the han system, Oyumi Domain consisted of several discontinuous territories calculated to provide the assigned "kokudaka", based on periodic cadastral surveys and projected agricultural yields. 
The domain was centered on what is now Chuo Ward and Midori Ward of the city of Chiba. 