Masakage was a son of Date Harumune. He was adopted by Rusu Akimune and became the lord of Takamori Castle in 1567. He went on to serve Date Terumune and Masamune with distinction at Hitadoribashi (1585), Ôsaki (1588), and elsewhere. During the Sekigahara Campaign (1600) Masakage led Date reinforcements into Dewa province to support the Mogami clan, under attack by the Uesugi, and clashed with troops under Naoe Kanetsugu. He afterwards received an income of some 20,000 koku.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005