筑前國
In 1585, after Shimazu invasion of Chikuzen Province, Shimazu advanced and captured Iwaya Castle from Otomo's. Later, Sōrin along with the "daimyō" of the Ryūzōji clan, they appealed to Toyotomi Hideyoshi to aid in holding back the Shimazu, who were beginning to extend their influence over Ōtomo and Ryūzōji lands. Though at first unsuccessful in enlisting Hideyoshi's aid, eventually the Shimazu took up arms against the Ōtomo, Shimazu seize Toshimitsu Castle, Funai Castle and defeated Sōrin at Battle of Hetsugigawa in 1586.