Sanemoto was a retainer of Satomi Yoshihiro. When Yoshihiro's horse was shot out from under him at the Second Battle of Konodai (1564), Sanemoto gave him his own mount. While Yoshihiro was making his retreat, Sanemoto shouted out that he was the Satomi general Yoshihiro and threw himself into the enemy - where he was presumably killed.
References
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005