was the head of the Ueda

Ueda

Ueda may refer to:*Siege of Ueda, in 1600*Ueda Electric Railway Bessho Line-Places:*Ueda, Nagano, a city in Japan*Ueda Castle in Japan*Ueda Domain of Japan*Ueda Glacier in Antarctica...

 Nagao clan following the Sengoku period

Sengoku period

The or Warring States period in Japanese history was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century. The name "Sengoku" was adopted by Japanese historians in reference...

 of the 16th century of Japan. Masakage was the brother-in-law of the famous 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...

, the "Dragon of Echigo". Masakage was the father of Uesugi Kagekatsu

Uesugi Kagekatsu

was a daimyo during the Sengoku and Edo periods of Japanese history. The son of Nagao Masakage and husband of Uesugi Kenshin's elder sister, Aya-Gozen. After his father died, he was adopted by Kenshin....

.

Even though Masakage may have been the brother-in-law of Kenshin, he still supported Nagao Harukage

Nagao Harukage

was Uesugi Kenshin's older brother, and successor to his father Nagao Tamekage in 1536. Harukage, being weak willed and sickly, was leader in name only. The real power was held by his chief advisor, Chiba Torataka, who organized Tamekage's former vassals behind him, apparently with the intention...

in a fight against Kenshin. Masakage later on became a retainer under Kenshin, but it is not known if he truly was assassinated on Kenshin's orders.