Masakuni at first served Murakami Yoshikiyo and held Yashiro Castle in Shinano. After the defeat of the Murakami at the hands of the Takeda, Masakuni came to serve the latter. He was killed at the Battle of Nagashino and was succeeded by his younger brother Hidemasa.
References
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005