Hosokawa Okimoto was the second son of Hosokawa Fujitaka, a noted retainer of the Ashikaga shōguns. He was awarded Tango Province by Oda Nobunaga, and his eldest son Hosokawa Tadaoki was one of the main generals of the Sengoku period and a close ally of Tokugawa Ieyasu. After the Battle of Sekigahara, Hosokawa Okimoto was awarded a minor fief 10,000 "koku" in Shimotsuke Province (Motegi Domain). This was only a tenth the size of the large domain in Kyushu awarded to his elder brother, with whom he had very strained relations. In 1616, for his participation in the Siege of Osaka, Okimoto was awarded an additional 6200 "koku" in Hitachi Province. He transferred his seat from Motegi to Yatabe, and this marked the start of Yatabe Domain. The domain consisted mostly of waste lands which were unsuited for agriculture, and from the beginning the domain was in a difficult financial situation with frequent famines. All requests for assistance to the wealthy Kumamoto Domain ruled by his brother and brother’s descendants were ignored.