Lifespan: Eishō 10 (1513) to 11/5 of Eiroku 5 (1562)
Title: Governor of Etchū
Lord: Amago Tsunehisa → Ōuchi Yoshitaka → Amago Haruhisa → Amago Yoshihisa → Mōri Motonari
Father: Honjō Kiyomitsu
Siblings: Masamitsu, Tsunemitsu, brother, sister (wife of Fukuya Yoshikane), sister (wife of Takeda Kurōdo)
Children: Takamitsu, Harumasa, Takatō, Yoshishige, Harumitsu, daughter (wife of Matsuda Hyōbu-Shōyu)
Honjō Tsunemitsu served as a bushō during the Sengoku period. Tsunemitsu was the lord of Yamabuki Castle in Iwami Province.
Tsunemitsu was a member of the Takahashi clan, a kokujin, or provincial landowner in Aki and Iwami provinces. His original surname was Fujiwara. He may have been the younger brother of Takahashi Okimitsu.
Initially, Tsunemitsu served Amago Tsunehisa. In the era of Amago Haruhisa (Tsunehisa’s lineal grandson), the Amago clan incurred a major defeat in battle against Mōri Motonari at the Siege of Yoshida-Kōriyama Castle which ran from 1540 to 1541. Afterwards, Tsunemitsu submitted to Ōuchi Yoshitaka.
In 1543, after Yoshitaka invaded Izumo Province and was defeated, Tsunemitsu reverted to the service of the Amago clan.
Tsunemitsu excelled in the military arts, contributing at the Collapse at Oshibara and the Battle of Gōrozaka. Counted upon by Haruhisa, he was appointed as the chamberlain of Yamabuki Castle on the front lines of Iwami Province. While a kokujin, or provincial landowner, of Iwami, Tsunemitsu also served as a direct retainer of the Amago. In 1561, after Mōri Motonari invaded Iwami in the wake of the death of Haruhisa, Haruhisa’s older brother, Amago Yoshihisa, unilaterally settled with the Mōri clan at the Peace Negotiations of Izumo and Aki. This shook bushō aligned with the Amago of Iwami including Tsunemitsu who supported the Fukuya clan in their rebellion against the Mōri. After the encirclement of Yamabuki Castle by the Mōri army, Tsunemitsu surrendered.
In 1562, out of suspicion of Tsunemitsu’s military prowess and personality, Motonari murdered him. Following the execution of Tsunemitsu, a majority of the Amago kokujin who had earlier switched sides to the Mōri reverted to the Amago.
The second son of Tsunemitsu, Honjō Harumasa, became an official of Kikkawa Motoharu. His son, Honjō Iefusa, served Kikkawa Hiroie (the third son of Motoharu), and descendants continued as retainers of the Iwakuni domain until the end of the Edo period.