Lifespan: 15xx to Tenshō 17 (1589) (?)
Other Names: Akimoto, Akisada, Baisessai (monk’s name)
Lord: Tamura Takaaki → Tamura Kiyoaki
Father: Tamura Yoshiaki
Siblings: Takaaki, Akimori, Yukiaki
Tamura Akimori served as a bushō during the Sengoku and Azuchi-Momoyama periods. He was a retainer of the Tamura clan and served as the lord of Ono Castle in Mutsu Province.
Akimori was born as the second son of Tamura Yoshiaki, a sengoku daimyō and the twenty-third head of the Tamura clan. Akimori’s year of birth is uncertain, but he was the younger brother of Tamura Takaaki.
In 1561, after the demise of Yoshiaki, Akimori served his older brother, Tamura Takaaki. Later, he served Takaaki’s lineal heir, Tamura Kiyoaki. In 1586, after Kiyoaki died without an heir, a succession struggle ensued within the family. This is known as the Tenshō Tamura Disturbance. Akimori conspired with Sōma Yoshitane and Gunji Toshiyoshi (a retainer of the Tamura) to fight against their uncle, Tamura Akiyori, who had joined with Date Masamune. In this battle, however, Akiyori, with the backing of Masamune, had an advantage and, in 1589, Akimori surrendered.
At the time of his surrender, Akimori is surmised to have been around ninety years old. There is a theory that he died in 1592, either from illness or was killed along with Gunji Toshiyoshi in a battle at Shizue Castle. His uncle, Akiyori, may have lived to be over one hundred years old. Consequently, there are theories questioning the details of their lives and whether the same names were used by different individuals in succession.
Within the Tamura clan, supporters of the Date were split into two rival factions, including the Akiyori (Gessai) faction and the Akimori (Baisessai) faction (and, with the Sōma faction, there were in fact three groups). During the Tenshō Tamura Disturbance, Akimori affiliated with the Date faction, but, according to one theory, after the end of the disturbance, owing to discord within the Date faction, he was defeated by Akiyori’s faction and ousted. Meanwhile, during the Kōriyama Conflict, he fought against the Sōma clan who came as reinforcements so it is undestood that he was not a member of that faction.