Lifespan: Kōshō 2 (1456) to 4/27 of Eishō 10 (1513)
Title: Governor of Settsu
Father: Takanashi Masataka
Siblings: Sister (formal wife of Izumi Masashige), Masamori, Hōjū-in (formal wife of Nagao Yoshikage) (?)
Wife: [Formal] Daughter of Hoshina clan (?)
Children: Sumiyori, daughter (formal wife of Nakajō Fujisuke), Kiyohide (?)
Takanashi Masamori served as a bushō during the late Muromachi and Sengoku periods. Masamori was responsible for the peak years of prosperity of the Takanashi clan. Masamori was the great-grandfather of Uesugi Kenshin. Masamori had a son named Takanashi Sumiyori.
In 1456, Masamori was born as the son of Takanashi Masataka. Similar to his father, Masamori received one of the characters in his name from Ashikaga Yoshimasa, the eighth shōgun of the Muromachi bakufu.
In 1495, owing to a dispute with Murakami Masakiyo regarding the Zenkō Temple, Masamori burned down the site. On this occasion, Masamori and Sumiyori brought back to their base the main statue of the bodhisattva.
The Takanashi clan was a kokujin, or provincial landowners, in Shinano. During the Eishō era (1504 to 1521), after defeating the Nakano clan, Masamori established a residence known as the Nakano-Otate and branch castle known as Kamogatake Castle in the township of Nakano in the Takai District of northeast Shinano Province. This served as a base for the Takanashi clan over the course of three generations (Masamori → Sumiyori → Masayori). An invasion by the Kai-Takeda caused Masayori to relocate to Iiyama Castle in the third month of 1559.
In 1507, Masamori joined when a maternal relative named Nagao Tamekage backed Jōjō-Uesugi Sadazane and launched a rebellion against Uesugi Fusayoshi, the military governor and seventh head of the Uesugi family of Echigo.
On 8/2 of 1507, Fusayoshi was subject to a sudden attack at his base by the forces under Sadazane and Tamekage. Fusayoshi relied upon his older brother, Uesugi Akisada (the deputy shōgun of the Kantō), to head toward the Kantō area; however, in the midst of fleeing, Masamori joined a pursuit by Tamekage’s soldiers who had stopped at Nōmine Castle in the Yasuzuke District of Echigo. Fusayoshi fled to the village of Matsunoyama, and, around 2:00 PM on 8/7, killed himself at the Amamizu Pass. This was one of a series of events comprising the Eishō Conflict that occurred in the Kantō and Hokuriku regions from 1506 to 1518.
In 1510, at the Battle of Nagamorihara, Masamori contributed to victory over Akisada who killed himself after being cornered. Thereafter, Masamori expanded his power including by eliminating the Nakano clan, but died in 1513. He was succeeded by his son, Sumiyori. Tamekage was thirty years younger than Masamori, so may have been the grandchild from a daughter married into another family, but there is a strong possibility that he was Masamori’s nephew.