Historic region of the Japanese island of Shikoku.
It dates at least to the Heian period , when Ki no Tsurayuki (868?–945?), editor of Japan's first imperially commissioned poetry anthology, wrote a fictional diary drawing on his experiences as governor of Tosa. In 1571 it became a unified domain ( han ) whose daimyo opposed Tokugawa Ieyasu when he consolidated his control of Japan in the early 17th century; this historical enmity became important at the time of the Meiji Restoration (1868), when samurai from Tosa, like those from Satsuma and Chōshū , helped overthrow the Tokugawa shogunate. See also Itagaki Taisuke ; Tokugawa period.