Masanobu was originally an attendant to Tokugawa Ieyasu, then became a retainer of Sakai Shogen, a militant ecclesiast lord of Ueno - this made him an enemy of Ieyasu, who opposed the Mikawa monto. When the monto were defeated in 1564, Masanobu fled, eventually returning to rejoin Ieyasu's service. While not a soldier of any renown due to a wound suffered in his youth, Masanobu was often to be found at Ieyasu's side for the next fifty years. He was made secretary to Tokugawa Hidetada and his efforts helped prevent a rift between Hidetada and Ieyasu when the former was late arriving at Sekigahara (1600). Masanobu was said to have been at the center of the scandal that disgraced the Okubo family (1614) and some scholars believe that Masanobu was a cunning schemer, noting his frequent feuds with Ieyasu's other chief retainers and his conspicuous refusal to accept rewards. It can be said that Ieyasu thought highly of Masanobu and was given to describing him as 'my friend'. He died of an illness in 1617.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005