Lifespan: Tenshō 11 (1583) to Genna 1 (1615)
Title: Master of the Imperial Guardsmen of the Right Division, Governor of Ōsumi
Clan: Chōsokabe → Tsuno
Lord: Chōsokabe Motochika → Chōsokabe Morichika → Katō Kiyomasa
Father: Chōsokabe Motochika
Siblings: Nobuchika, Kagawa Chikakazu, Tsuno Chikatada, Morichika, Ukon-Taifu, Yasutoyo
Children: Sokabe Shigeyoshi
Chōsokabe Ukon-Taifu served as a bushō during the Azuchi-Momoyama and early Edo periods. His real name is unknown. He held the title of ukon-taifu, or Master of Imperial Guardsmen of the Right Division, and Governor of Ōsumi.
In 1583, Ukon-Taifu was born as the fifth son of Chōsokabe Motochika, the sengoku daimyō of Tosa Province. His mother was a consort named Koshōshō. Upon orders of Motochika, he served as a monitor for the Kataoka clan in addition to serving as a chief priest in Shimohachigawa-Doi.
In the wake of the Battle of Sekigahara on 9/15 of Keichō 5 (1600), Ukon-Taifu’s older brother, Chōsokabe Morichika, was removed from his position, after which Ukon-Taifu served Katō Kiyomasa of Higo Province. Ukon-Taifu also helped raise Chōsokabe Moritane, the grandson of Morichika.
In 1615, at the Summer Campaign in the Siege of Ōsaka, Ukon-Taifu joined the Toyotomi clan and, along with Morichika, was compelled to commit seppuku. A retainer named Komiyazaki Kyūbei martyred himself along with his lord. According to one account, Ukon-Taifu had not previously witnessed an act of seppuku, so Kyūbei cut a cross on his own stomach and said you cut this way, whereupon Ukon-Taifu laughed and then resolutely followed his model. His grave is unknown.
To avoid being pursued by the Yamauchi family, descendants of the Chōsokabe family changed their surnames to Sokabe and Soga.