Yoshihisa was the second son of Amako Haruhisa and succeeded his father in 1562. He attempted to resist the growing power of the Môri but was unable to expel the latter when they began an invasion of Izumo in 1563. He lost Shiga castle but managed to hold off an initial assault on Gassan-Toda in 1564. The Môri besieged Gassan-Toda in 1565. Yoshihisa lost the confidence of his men when he executed one of his chief retainers, Uyama Hisanobu, on erroneous charges of treason. Faced with starvation, Yoshihisa surrendered in the 1st month of 1566 and was placed under confinement in Aki province with his younger brothers (Tomohisa and Hidehisa) for the following 16 years. He was eventually allowed an income of some 570 koku and moved to Nagato province, where his income was increased to around 1,300 koku. He at length became a monk and died at the age of 74.