Nagao Norinaga served as a bushō during the Sengoku period.  He was the kasai, or head of house affairs, for the Yamauchi-Uesugi family, based in Kōzuke Province.

In 1503, Norinaga was born as the eldest son and designated heir of Nagao Kagenaga.  Norinaga appears to have received one of the characters in his name from Uesugi Norifusa.

Around 1524, he inherited the headship of the Ashikaga-Nagao clan and the role of head of house affairs for the Yamauchi-Uesugi family.  In 1528, his father, Kagenaga, died of illness.  This same year, in connection with the coming-of-age ceremony for Kamewakamaru, the eldest son and designated heir of Ashikaga Takamoto (the Koga kubō), Norinaga negotiated through Nagao Tamekage for Kamewakamaru to receive one of the characters from the name of Ashikaga Yoshiharu, the twelfth shōgun of the Muromachi bakufu.  Kamewakamaru then adopted the name of Ashikaga Haruuji while Norinaga joined in the ceremony.  On 12/28 (the day after the ceremony), Norinaga received the honorary title of Governor of Tajima.

The Nagao clan in Kōzuke Province had for generations been divided between the Shiroi-Nagao family and the Sōja-Nagao family.  In 1528, after the assassination of Nagao Kagenobu ended the lineal succession of the Shiroi-Nagao clan, Norinaga joined the Sōja-Nagao in an effort to bring the situation under control by backing Nagao Norikage (the adopted son of Kagenobu) as the eighth head of the Shiroi-Nagao.  Owing to internal conflicts, even after the deputy shōgun of the Kantō transitioned from Uesugi Norihiro to Uesugi Norimasa, Norinaga continued to serve as the head of house affairs.  In 1548, at the coming-of-age ceremony for Ashikaga Fujiuji, Norinaga’s son, Nagao Masanaga, attended.  To enable Masanaga to participate, Norinaga is surmised to have retired and transferred the role of head of house affairs to Masanaga.