Fujibayashi Nagato-no-kami () was a samurai and ninja operative during Japan's Sengoku period. His birth and death dates remain unknown. His real name is believed to have been Yasutoyo ().
Fujibayashi hailed from Yufune village in Ahaigun, northern Iga ProvinceâÂÂnow Higashi-Yufune in Iga, MieâÂÂwhich bordered Kà Âka District in à Âmi Province. There are various theories about his real name, including Masayasu and Yasutoyo. He controlled Yufune-go (Ueno City, Mie Prefecture), which located in the northern part of Iga Province, and had authority over the ninjas from Kà Âka District, Shiga.
Initially, he served Imagawa Yoshimoto in Suruga Province, residing in Sunpu (modern-day Shizuoka). During this time, he is believed to have developed a friendship with Yamamoto Kansuke prior to Kansuke's service under Takeda Shingen, and may have learned military strategy from him. Following internal turmoil in Iga, he resigned and returned home.
Fujibayashi maintained close ties with the Rokkaku clan due to his sister's relationship with Rokkaku Yoshikata. During the Eiroku era, when Yoshikata faced difficulties capturing Sawayama Castle from the rebelling Dodo clan, he requested help from Fujibayashi. In response, Iga ninja under Tateoka DÃ Âjun were dispatched, contributing to the Rokkaku victory.
His later activities are largely unknown. By the time of the Tenshà  Iga War, his son Fujibayashi Yasumasa had succeeded him. After the defeat, Nagato is said to have survived the Second Tensho Iga War in 1581 by siding with Nobunaga, but the details are unknown.
The Fujibayashi clan fled and sought protection under the Tokugawa clan. The family later returned to Yufune and entered the service of the Tà Âdà  clan of the Tsu Domain.
A descendant, Fujibayashi Yasutake, authored the famous ninja manual Bansenshà «kaiâÂÂan essential record of Iga and Kà Âka ninja traditions.
His descendant, Fujibayashi Yasutake, has written Bansenshukai, A manual of Ninjitsu, in 1676 during the early years of Tokugawa Shogunate.
Remains of Fujibayashi Nagato former fortress in Ahaigun still exist in the 20th century.
His grave, believed to be that of the Fujibayashi family, was relocated from the ruins of his former castle to Shà Âkaku-ji in Higashi-Yufune, Iga. It is now designated a municipal historic site.