Ayukawa Kiyonaga served as a bushō and retainer of the Uesugi clan during the Sengoku and Azuchi-Momoyama periods. Kiyonaga was the lord of Ōbasawa Castle in Echigo Province.
The Ayukawa clan were members of the Agakita Group – kokujin, or provincial landowners, in northern Echigo who were fiercely independent. The Ayukawa controlled territory in the Iwafune District.
In 1527, the Fusai Temple was established in the foothills below the base for the clan at Ōbasawa Castle.
In 1530, after Jōjō Sadanori raised arms against Nagao Tamekage, the deputy military governor of Echigo, other clans associated with the Agakita Group sided with the Jōjō clan. In 1539, Kiyonaga came into conflict with an ally named Honjō Fusanaga in regard to control of Shimo-Oshima Castle situated on the border. Kiyonaga plotted with Ogawa Nagasuke (Nagafusa’s younger brother and provincial landowner) to attack Honjō Castle, causing Fusanaga to flee in defeat to Dewa Province. After the demise of Nagao Tamekage, Nagao Kagetora (later known as Uesugi Kenshin) inherited the Nagao family, whereupon Kiyonaga came into his service. At the Fourth Battle of Kawanakajima, Kiyonaga joined Honjō Shigenaga and Irobe Katsunaga to prepare for a detached unit of the Takeda army, and after converging with the Uesugi army, engaged in fierce combat against the Takeda army.
In 1568, Honjō Shigenaga responded to solicitations from Takeda Shingen to rebel against Kenshin in an event known as the Revolt of Honjō Shigenaga. Kiyonaga, however, refused to join the effort, remaining loyal to Kenshin. Isolated, Shigenaga surrendered to Kenshin and was forgiven on the condition that a portion of the territory held by the Honjō clan be given to the Ayukawa clan. Owing to resentment at this outcome, in 1571, Shigenaga subdued Kiyonaga and Kiyonaga is believed to have died at this time. Moreover, Shigenaga was admonished by Kenshin and his landholdings temporarily seized, only later to be returned following an apology.