Yoshiyasu was a son of Satomi Yoshiyori. He submitted to Toyotomi Hideyoshi and assisted him in the Odawara Campaign, thus being present for the downfall of the Satomi's longtime enemy, the Hôjô. Afterwards he was made to give up his holdings in Kazusa and Shimôsa but was confirmed in Awa, with an income of some 92,000 koku. He joined Tokugawa Ieyasu in the Sekigahara Campaign and had his holdings increased to 120,000 koku.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005