Oyama Tomosato

Oyama Tomosato (died 1346), childhood name Jōkenmaru and first called Tomouji, was the ninth head of the Oyama warrior house of Shimotsuke Province. In 1335 his father Hidetomo was killed in the Nakasendai Rebellion, and Tomosato inherited the family domains and shugo post as a child under a guardian.

In 1337 Kitabatake Akiie's Southern Court army seized Oyama Castle and captured him, but Yūki Munehiro interceded to spare his life. Around 1340 he was reportedly at war with his Northern Court-aligned brother Ujimasa, and died suddenly in May 1346 without children, so Ujimasa succeeded him.