The clan is associated with
Tosa Province in modern-day
Kōchi Prefecture on the island of
Shikoku.
Chōsokabe Motochika, who unified Shikoku, was the twenty-first
daimyō (or head) of the clan. In their early history of the
Sengoku period,
Chōsokabe Kunichika's father Kanetsugu, was killed by the Motoyama clan in 1508. Therefore, Kunichika was raised by the aristocrat Ichijō Husaie of the Ichijō clan in Tosa Province. Later, towards the end of his life, Kunichika took revenge on the Motoyama clan and destroyed them with the help of the Ichijō in 1560. Kunichika would go on to have children, including his heir and the future Daimyo of the Chōsokabe, Motochika, who would go on to unify
Shikoku. First, the Ichijō family was overthrown by Motochika in 1574. Later, he gained control of the rest of Tosa due to his victories at the Battle of Watarigawa in 1575. He then also destroyed the Kono and the Soga clan. Over the ensuing decade, he extended his power to all of Shikoku in 1583. However, in 1585,
Toyotomi Hideyoshi (
Oda Nobunaga's successor) invaded that island with a force of 100,000 men, led by
Ukita Hideie,
Kobayakawa Takakage, Kikkawa Motonaga,
Toyotomi Hidenaga, and
Toyotomi Hidetsugu. Motochika surrendered, and forfeited
Awa,
Sanuki, and
Iyo Provinces; Hideyoshi permitted him to retain Tosa. Under Hideyoshi, Motochika and his son
Chōsokabe Nobuchika participated in the invasion of neighboring
Kyūshū, in which Nobuchika died. In 1590, Motochika led a naval fleet in the Siege of Odawara, and also fought in the
Japanese invasions of Korea led by Toyotomi Hideyoshi in 1592. After Motochika died in 1599 at age 61, the next clan leader was his son
Chōsokabe Morichika. He led the clan forces in support of the Toyotomi at the
Battle of Sekigahara. After 1600, the Chōsokabe were removed as daimyo of Tosa.
Shirō Sōkabe, the 19th century missionary, was a descendant of the Chōsokabe clan. ==Clan heads==