The was a family of daimyo

Daimyo

is a generic term referring to the powerful territorial lords in pre-modern Japan who ruled most of the country from their vast, hereditary land holdings...

, feudal lords who built and controlled Kasugayama Castle

Kasugayama Castle

' was the primary fortress of the Japanese warlord Uesugi Kenshin during the Sengoku period. It is situated in what is now the city of Jōetsu, Niigata prefecture, and was originally built and ruled by the Nagao clan....

 and the surrounding fief, in what is now Niigata Prefecture

Niigata Prefecture

is a prefecture of Japan located on the island of Honshū on the coast of the Sea of Japan. The capital is the city of Niigata. The name "Niigata" literally means "new lagoon".- History :...

. Nagao Kagetora, adopted by Uesugi Norimasa

Uesugi Norimasa

was a daimyō of feudal Japan, and held the post of Kantō Kanrei, the Shogun's deputy in the Kantō. He is perhaps best known as the adoptive father of Uesugi Kenshin, one of the most famous warlords in Japanese history....

, became lord of the castle in 1548, taking the name Uesugi Kenshin

Uesugi Kenshin

was a daimyo who ruled Echigo province in the Sengoku period of Japan.He was one of the most powerful lords of the Sengoku period. While chiefly remembered for his prowess on the battlefield, Kenshin is also regarded as an extremely skillful administrator who fostered the growth of local industries...

 and effectively changing the ruling clan of Kasugayama from Nagao to Uesugi. Those members of his family who retained the Nagao name became retainers to the Uesugi family.

Nagao Family Members of Note

• Nagao Tamekage
  Nagao Tamekage
  was a retainer of Japanese feudal lord Uesugi Fusayoshi, and a daimyo in his own right, during Japan's Sengoku period. According to some scholars, such as George Bailey Sansom, Nagao Tamekage's career makes him representative of the emergence of the daimyo, and the shift of regional power from the...
  
   (d. 1536), was the father of Nagao Kagetora, who would become Uesugi Kenshin.
• Uesugi Kenshin
  Uesugi Kenshin
  was a daimyo who ruled Echigo province in the Sengoku period of Japan.He was one of the most powerful lords of the Sengoku period. While chiefly remembered for his prowess on the battlefield, Kenshin is also regarded as an extremely skillful administrator who fostered the growth of local industries...
  
   (1530-1578), originally Nagao Kagetora, is one of the most famous warlords in Japanese history.
• Nagao Fujikage
  Nagao Fujikage
  Nagao Fujikage was a samurai of the Nagao clan who served under Uesugi Kenshin during Japan's Sengoku period. He was counted among Kenshin's Twenty-Eight Generals and fought on the left flank at the fourth Battle of Kawanakajima in 1561.-References:...
  
   (dates unknown) fought under Kenshin at the fourth battle of Kawanakajima
  Battles of Kawanakajima
  The ' were fought in the Sengoku Period of Japan between Takeda Shingen of Kai Province and Uesugi Kenshin of Echigo Province in the plain of Kawanakajima, in the north of Shinano Province. The location is in the southern part of the present-day city of Nagano.The five major battles took place in...
  
  in 1561.