丹後国
Yonekura Masanaga was born as the 3rd son of Kutsuki Masatsuna, "daimyō" of Fukuchiyama Domain in Tango Province. In 1812, on the death of the 6th "daimyō" of Mutsuura Domain (Yonekura Masanori), he was adopted into the Yonekura clan. In June 1812, he was presented before "shōgun" Tokugawa Ienari and confirmed as the "daimyō" of Mutsuura.