was the 8th and final daimyà  of Mutsuura Domain in southern Musashi Province, Honshà «, Japan (modern-day Kanagawa Prefecture) during the Bakumatsu period.
Yonekoto Masakoto was the 6th son of the 7th daimyà  of Mutsuura Domain, Yonekura Masanaga. In May, 1868, he was presented before Shà Âgun Tokugawa Iesada in a formal audience and on June 24, 1860, due to his father's retirement due to illness, became the head of the Yonekura clan, and daimyà  of Mutsuura Domain. He served in a number of ceremonial posts within the administration of the Tokugawa shogunate, including guard duty at Osaka Castle, and participated in both the First Chà Âshà « expedition and the Second Chà Âshà « expedition. In 1867, he was assigned guard duty over the Yokosuka Naval Arsenal; however in 1868 during the Boshin War of the Meiji Restoration, he capitulated to the Satchà  Alliance forces without a struggle. For this reason, he was confirmed as domain governor of Mutsuura in June 1869. He left public service with the abolition of the han system in July 1871.
In 1887, he was ennobled with the title of viscount (shishaku) under the kazoku peerage system.
Yonekura Masakoto was married to a daughter of Suwa Tadamichi, daimyà  of the Suwa Domain in Shinano Province .