Yamana Tsunetoyo served as a bushō during the late Muromachi period.
In 1466, Tsunetoyo was born as the eldest son of Yamana Masatoyo, a bushō, shugo daimyō, and the military governor of Yamashiro, Aki, Tajima, and Bingo provinces. Masatoyo was the successor to Yamana Sōzen, the commander-in-chief of the Western Army during the Ōnin-Bunmei War.
In the fourth month of 1474, Tsunetoyo’s father, Masatoyo, who was aligned with the Western Army during the Ōnin-Bunmei War, settled with the Eastern Army and met Ashikaga Yoshihisa, the ninth shōgun of the Muromachi bakufu. The eight-year-old son accompanying him during this visit appears to have been the young Tsunetoyo. Twelve years later, in the ninth month of 1486, a member of the Yamana family died at age twenty and he is recorded to have died early as shown in genealogical records. These references appear to be in regard to Tsunetoyo.
In 1485 (the year before the death of Tsunetoyo), his father, Masatoyo, led an expedition to Harima Province, the home province of the Akamatsu clan, and incurred a major defeat. This resulted in the loss of many senior retainers of the clan. The ensuing death of Tsunetoyo shook the Yamana clan, triggering conflict among clan members over the choice of a successor.