- Death: 1552
- Title: Bitchû no Kami
Masatatsu began a branch of the Oyamada separate from that of Nobushige. He was said to have been a expert of defensive warfare but was killed in battle with the Murakami in 1552. He was the father of Oyamada Masayuki and Masasada.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005