Masatsugu was the second son of Kanamaru Chikuzen no Kami Torayoshi (d. 1572). He fought in many of Takeda Shingen's battles, notably the Fourth Battle of Kawanakajima. He contemplated killing himself when Shingen died in 1573 but Kosaka Masanobu managed to convince him to carry on in the service of the Takeda. He was killed just two years later, shot to death in the Battle of Nagashino. His three sons were among the final supporters of Takeda Katsuyori and died fending off Oda troops while their lord committed suicide at Temmokuzan.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005