Nagao Akinaga served as a bushō from the Sengoku to early Edo periods.  He served as the head of the Ashikaga-Nagao clan based in Kōzuke Province.

In 1556, Akinaga was born as the third son of Yura Narishige.  His mother was Myōin-ni.  He wed the daughter of Nagao Masanaga (later known as Kagenaga), the head of the Ashikaga-Nagao clan.  After the demise of Kagenaga in 1569, Akinaga inherited the headship of the clan.  Kagenaga’s base at Tatebayashi Castle, however, was granted to another son-in-law named Hirota Naoshige.

In 1582, Akinaga, along with his older brother, Yura Kunishige, served Takigawa Kazumasu.  Later, he submitted to the Gohōjō clan.  In 1585, Akinaga engaged in a dispute with Sano Munetsuna, the head of the Sano clan of Shimotsuke Province and killed him.  In 1590, during the Conquest of Odawara led by Toyotomi Hideyoshi, Akinaga holed-up in Odawara Castle and fought against the assault, so, after the demise of the Hōjō clan, his landholdings were confiscated and he became a rōnin, or wandering samurai.  For a while, he served Satake Yoshinobu of Hitachi Province but, thereafter, wandered again.  His son, Nagao Tomokage, served Doi Toshikatsu, a hereditary daimyō in Shimōsa Province, later becoming a chief retainer.