At the time of the Battle of Sekigahara, Hisanobu fought on the Toyotomi side, although his father defected to the Tokugawa side and burned down his castle in Hirado as a gesture of loyalty to the new shōgun, Tokugawa Ieyasu.
At the Battle of Sekigahara, Hisanobu fought for Toyotomi despite his father's defection to Tokugawa and subsequent destruction of their castle in Hirado as a show of support for the new shōgun, Tokugawa Ieyasu.