Lifespan: Meiō 1 (1492) to 11/1 of Tenbun 23 (1554)
Lord: Amago Tsunehisa → Amago Haruhisa
Father: Amago Tsunehisa
Siblings: Masahisa, Kunihisa, Enya Okihisa
Wife: [Formal] Sister of Tako Tadashige
Children: Sanehisa, Toyohisa, Takahisa, Matashirō, Yoshirō, daughter (formal wife of Amago Haruhisa), daughter (wife of Ōkawara Sadanao), daughter (wife of Shinji Takayoshi), daughter (wife of Yuhara Nobutsuna, Kazuhisa)
Amago Kunihisa was a family member of the Amago clan and second son of Amago Tsunehisa, the sengoku daimyō of Izumo Province. Kunihisa received one of the characters in his name from Hosokawa Takakuni, a kanrei, or deputy shōgun, of the Muromachi bakufu, in 1512. Kunihisa was adopted into the Yoshida clan, a branch of the Sasaki clan descended from the powerful Uda Genji line. The Yoshida were gōzoku, or a family of local wealth and influence, in addition to hōkōshū, officials of the Muromachi bakufu with exclusive privileges to an administrative office in Izumo under direct jurisdiction of the bakufu to which entry by the shugo was prohibited. Having his younger brother, Okihisa, adopted by the Enya clan reflected a broader strategy by their father, Tsunehisa, to secure his relationships with powerful kokujin in Izumo through familial ties. Kunihisa succeeded to the territory governed by the Enya in the western portions of Izumo after Okihisa rebelled and was defeated.
Kunihisa served as commander of the shingūtō, an elite force of soldiers operating under the name of the Shingū Valley located in the foothills to the north of Gassantoda Castle. Kunihisa inherited his command from Tsunemitsu. The organization wielded considerable power in Izumo, controlling the eastern portions of Izumo held by the Yoshida clan, as well as the western portions held by the Enya after the failed rebellion by Okihisa. The shingūtō contributed to the expansion of the Amago influence in neighboring provinces including Aki and Bingo. Kunihisa and his eldest son, Sanehisa, were so proud of the fearsome unit that it led to discord between them and Amago Haruhisa, lord of the Amago clan, and other senior retainers.
In 1524, Kunihisa participated in a campaign led by Tsunemitsu in Hōki Province known as the Taiei no satsuki kuzure, attacking the castles of Odaka and Ueshi, among others.
In 1540, Haruhisa planned an attack against the Mōri in Aki Province to counter the Ōuchi. Kunihisa led an expeditionary force of 3000 men to Bingo Province. The army crossed the Gō River from Bingo to open a route to Yoshida-Kōriyama Castle, striking the Shishido, only to be defeated in a counterattack. Haruhisa then commanded 30,000 mounted soldiers on a failed expedition to the castle. Kunihisa later led the shingūtō in a crushing attack on Ōuchi Yoshitaka after his invasion of Izumo at the Battle of Yoshida-Kōriyama Castle. Amago Hisayuki, de facto leader of the shingūtō, was killed during this conflict.
Kunihisa led subsequent expeditions to Bingo, Hōki, and surrounding provinces, achieving victories that expanded the influence of the Amago in the western region so that he was regarded as the guardian of the clan. Nevertheless, he had a frequent difference of opinion with his son-in-law, Haruhisa, in regard to plans. Direct control by the shingūtō over the territories held by the Yoshida and Enya gave them more influence than Haruhisa in Izumo. Moreover, many of them displayed arrogance based on their military exploits, causing conflicts with other retainers in the clan. This led to a gradual falling out in Kunihisa’s relationship with Haruhisa.
In addition to the challenges posed by the shingūtō, Haruhisa depended upon Kunihisa’s influence with the Kizuki no Ōyashiro, a major shrine whose proprietors sought to manage political and military affairs on their own accord. Haruhisa desired to bring the shrine under the direct control of the Amago clan, causing tensions based on Haruhisa’s opposition to the influence of Kunihisa and the shingūtō with respect to Kizuki no Ōyashiro and its environs. Haruhisa held sway over the western portions of Izumo indirectly via Kunihisa.
In 1554, following the death of Haruhisa’s formal wife, who was the daughter of Kunihisa, Haruhisa purged the leaders of the shingūtō, including Kunihisa and his son, Amago Sanehisa, to reimpose control over the clan. Kunihisa was assassinated while departing the castle, while Sanehisa killed himself in the shingūtō quarters. Remaining members either killed themselves or fled, marking the end of the elite force. By eliminating Kunihisa and his role as an intermediary for western Izumo, Haruhisa could intervene more directly in the affairs of the Kizuki no Ōyashiro, and nearly complete his goal to govern the entire province of Izumo.