Masayoshi was a son of Kanematsu Kiyohide. He was at first a minor retainer of Oda Nobunaga, and after 1582, of Oda Nobukatsu. He was dismissed from Nobukatsu's service in 1590 and went to serve Toyotomi Hideyoshi, who gave him some land in Mino province. In 1593 he went to serve Toyotomi Hidetsugu but, when the latter was made to commit suicide in 1595, he went back to Hideyoshi's service. After 1600 he managed to ingratiate himself with the Tokugawa and served Tokugawa Yoshinao in Owari province. He is best remembered for an incident that occurred earlier in his career. While in the service of Nobunaga in 1573, he was present for the fall of the Asakura clan of Echizen province. At a place called Toneyama, Masayoshi pursued a lone enemy horseman into the mountains, whence he killed him and took his head. However, during his pursuit he lost his shoes and his bare feet became dyed red with the mountain soil. When Nobunaga saw this, he gave Masayoshi the ashinaka (un-heeled Japanese sandals) that had been hanging from his waist, saying "I hadn’t thought that something such as this would come in handy at a time like this."
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005