Yorikata Kono was born in Imabari Castle, Iyo Province, in Shikoku, the realm of the feudal Kono clan, led by his father Michinao. Yorikata was mothered by a Sogo princess, Kyua Watanabe. In 1540, he came of age and became a general in the Kono army, and fought his first battles against the Ichijo of Tosa Province. They fought their vassals, the Chosokabe, who took over Tosa in 1545 after rebelling against the Ichijo, now led by Kunichika Chosokabe. Kunichika died in battle in the Battle of Tosa Fields, and his general Ietoyo Kira commanded his armies thereafter. Yorikata's father fought against the Chosokabe clan, hoping to annex Tosa from the seemingly weak enemy. Yorikata commanded a field army of 600 Kono troops in an invasion of Tosa Province, supervised by Michinao Kono, and met Ietoyo Kira near Kochi Castle, the capital of Tosa. Yorikata led a charge with his whole army, converging on the weak Yari Ashigaru spearmen, when the Bow Ashigaru archers behind the spearmen (and concealed in the woods) released their arrows. In the end, Yorikata was shot and killed by the Chosokabe, and his father was wounded. Yorikata's death left a stain on Kono-Chosokabe relations, and the Chosokabe would eventually annex Iyo.