Tadamoto's family had once been daimyô in Shinano province. He served Yamagata Masakage and might have been a cousin or other relative. He fought at the battles of Mimasetoge and Nagashino, afterwards becoming a commander of infantry. He attempted to lead a relief force to Takato castle in 1582 but was killed in the attempt.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005