Shigenaga was the son of Honjô Fusanaga. He entered the service of Uesugi Kenshin sometime prior to 1558 and held Honjô castle. He was active in the fighting around Kawanakajima and in the Kanto though he disobeyed Kenshin on a number of occasions. He submitted with his lands to Takeda Shingen in 1568 but was later forgiven - only to defy Kenshin over the war against the Oda in 1577. Shigenaga nonetheless went on to serve Kagekatsu. He was the owner of a famous blade by Masamune.
- Initial text from Samurai-Archives.com FWSeal & CEWest, 2005