He was born to Amago Masahisa in 1553. In the following year, Katsuhisa's father and grandfather were killed by Amago Haruhisa, leading Katsuhisa to become a Buddhist monk. After the Amago clan was overthrown by Mōri Motonari in 1566, Yamanaka Yukimori supported Katsuhisa against the Mōri clan in 1568. He lost to Mōri Terumoto at Nunobeyama in 1570 and fled to the island of Oki.
Katsuhisa later returned from Oki and captured Tajima and Inaba provinces, defending Kozuki Castle for Toyotomi Hideyoshi against the Mōri clan. He was attacked by Kobayakawa Takakage and Kikkawa Motoharu, was defeated, and committed suicide.
This article incorporates text from OpenHistory.