Okimoto also showed outstanding performance in the Osaka no Jin (The Siege of Osaka) which started in 1614, and as a result, he received an additional 6,200 goku crop yields in both Tsukuba and Kawachi Counties in Hitachi Province, leading him to establish Yatabe Domain.
慶長19年（1614年）からの大坂の陣でも功績を挙げて、元和2年（1616年）に常陸国筑波・河内両郡に6200石を加増され、谷田部藩を立藩した。