Lifespan: Unknown to second month of Genki 1 (1570)
Lord: Amago Yoshihisa → Matsunaga Hisahide → Amago Katsuhisa
Father: Yokomichi Kiyotaka
Siblings: Hidetsuna, Takamitsu (Gensuke), Takamune (Norimasa (?))
Yokomichi Hidetsuna served as a bushō during the Sengoku period. He was a retainer of the Amago clan. Hidetsuna is also counted among the Amago jūyūshi, or the Ten Warriors of the Amago, a group of elite soldiers revered after the Sengoku period.
The Yokomichi clan originated from the village of Yokomichi in the Ōie-no-shō Nishi township in the coastal Nima District of Iwami Province.
Hidetsuna was born as the son of Yokomichi Kiyotaka, an elder of the Amago clan, the sengoku daimyō of Izumo Province.
Hidetsuna, together with his younger brothers, Takamitsu and Takamune, are frequently referred to in military chronicles as the Yokomichi brothers.
In 1566, the Mōri army captured Gassantoda Castle in Izumo, whereupon the status of the Amago clan as a sengoku daimyō family came to an end. After surrendering, Hidetsuna attempted to accompany his lord, Amago Yoshihisa, who was sent to Aki Province. The Mōri, however, did not permit him, so Hidetsuna and his younger brothers went to seek protection from Matsunaga Hisahide of Yamato Province. Before long, they left Hisahide and joined Yamanaka Yukimori to back Amago Katsuhisa in a bid to revive the Amago clan with support from Oda Nobunaga. This effort yielded temporary success in fighting against the Mōri army across Izumo; however, in the second month of 1570, the Amago revival army with approximately 6,000 soldiers suffered a bitter defeat to a larger Mōri army at the Battle of Fubeyama. Owing to injuries incurred in the course of the battle, Hidetsuna tried to rest on a roadside when he spotted the husband of his niece, Nakai Zenzaemon. Dropping his guard, he began to explain to Zenzaemon that he was injured whereupon Zenzaemon stabbed him with a spear and took his head. This owed to the fact that, ten days earlier, Zenzaemon had surrendered to the Mōri, making him an enemy of Hidetsuna despite their familial ties.