Ohatsu's younger sister, Oeyo, also known as Ogō, was the main wife of Shogun Tokugawa Hidetada and the mother of her successor Iemitsu Tokugawa. The Kyogoku clan allied with Tokugawa Ieyasu of Eastern army against Western army in Sekigahara Campaign. The Western army was led by Ishida Mitsunari and other vassals loyal to Toyotomi. Ohatsu was in the castle when the siege of Otsu occurred. Ohatsu and Oeyo were allies of the Eastern Army, their sister, Yodo-dono, was one of the prominent anti-Tokugawa (Eastern army) figures during Sekigahara and later during the siege of Osaka.