Hamamatsu Domain
Ōta Suketsugu was the second son of Ōta Sukemune, the daimyō of Hamamatsu Domain. His elder brother Ōta Sukemasa entered the service of "Shōgun" Tokugawa Iemitsu at an early age, but was disinherited in 1651 by order of Iemitsu. Sukesugu was confirmed as head of the Ōta clan on his father's retirement in 1671. On December 18, 1671, he became daimyō of Hamamatsu. He entered the administration of the Tokugawa shogunate under "Shōgun" Tokugawa Ietsugu in 1673 as a "Sōshaban" (Master of Ceremonies) at Edo Castle and on July 26, 1676, he was appointed a "Jisha-bugyō" (Commissioner of Shrine and Temples). On June 19, 1678, he received the post of "Osaka jōdai" (Castellan of Osaka). In order to take up his posting to Osaka, he surrendered Hamamatsu Domain back to the shogunate, in exchange for 20,000 "koku" of additional territories scattered in Settsu, Kawachi and Shimōsa provinces.