Lifespan: Tenbun 22 (1553) to 3/21 of Kanei 3 (1626)
Title: Governor of Tajima
Lord: Sanada Masayuki → Sanada Nobuyuki
Father: Yazawa Yoritsuna (younger brother of Sanada Yukitaka)
Siblings: Yoriyasu, Yorikuni
Adopted Children: Yorikuni
Yazawa Yoriyasu served as a bushō from the Sengoku to early Edo periods. He was a retainer of the Sanada clan. He had the common name of Sanjūrō.
From an early age, he followed his father who served as the chamberlain of Numata Castle. During the Tenshō era (1573 to 1592), the duties as castle chamberlain were assigned to Yoriyasu.
In 1585, when Sanada Masayuki’s second son, Sanada Nobushige, was sent to Uesugi Kagekatsu as a hostage, Yoriyasu accompanied him as a member of the security detail. That same year, at the First Battle of Ueda, together with reinforcements from Uesugi Kagekatsu, Yoriyasu holed-up in Yazawa Castle and repelled 1,500 Yoda forces, causing Ōkubo Tadayo and his forces to scatter in the ensuing pursuit of the attackers. From this year forward, there are few accounts of the actions of his father, Yoritsuna. Moreover, this year marked the beginning and the end of letters jointly signed by Yoriyasu and Yoritsuna, so it is surmised that he succeeded his father around this time.
During the Battle of Sekigahara, Yoriyasu affiliated with Sanada Nobuyuki, delivering Nobuyuki’s son, Sanada Nobumasa, as a hostage to Tokugawa Ieyasu. After Nobuyuki became the head of the clan, Yoriyasu continued to serve him. During the Siege of Ōsaka, Yoriyasu supported Nobuyuki’s sons (Sanada Nobuyoshi and Nobumasa) who deployed on behalf of their father. With respect to the deployment, Nobuyuki wrote in a letter to Yoriyasu to step-in and always remain vigilant.
Yoriyasu died in 1626. He did not have children, but, according to his last will, he was succeeded by his younger brother, Yazawa Yorikuni. Thereafter, his descendants supported the Sanada clan for generations as chief retainers of the Matsushiro domain.