Tosa Province
In the Sengoku period, Sanuki was ruled by the Miyoshi clan. The Miyoshi were invaded by Chōsokabe clan in Tosa Province and lost Sanuki Province. Finally Chōsokabe lost a battle against Toyotomi Hideyoshi, who rewarded his vassals by assigning Takamatsu Castle to Ikoma Chikamasa , and Sogō Castle to Sogō Masayasu.