Satomi clan
The original Sanuki Castle was built by the Satomi clan, rulers of most of the Bōsō Peninsula during the Sengoku period. Following the Battle of Odawara in 1590, the Kantō region by was assigned to Tokugawa Ieyasu by the warlord Toyotomi Hideyoshi, who also restricted the Satomi to Awa Province for their lukewarm support of his campaigns against the Later Hōjō clan. Tokugawa Ieyasu appointed Naitō Ienaga, one of his hereditary retainers, to be "daimyō" of the newly formed 20,000 "koku" Sanuki Domain.