Lifespan: Unknown to 15xx
Title: Lieutenant of Outer Palace Guards of the Right Division
Father: Kōsokabe Michinaga
Adopted Children: Hidemichi (younger brother), Chikayasu (third son of Chōsokabe Kunichika)
Kōsokabe Chikahide served as a bushō during the Sengoku [period. He was a kokujin, or provincial landowner, in Tosa Province.
Chikahide was born as the eldest son of Kōsokabe Michinaga, a kokujin in the southeast portion of the Kami District of Tosa.
After inheriting the headship of the clan, in 1526, Chikahide attacked the Aki clan, landlords in the Aki District of Tosa, but lost his son and designated heir, Kōsokabe Hideyoshi, en route to suffering a major defeat. As a result, he adopted his younger brother, Kōsokabe Hidemichi. Later, he adopted the monk’s name of Sensen and retired.
The Kōsokabe can, however, began to wane in influence. Seeking a revival and fearing the expansion of power wielded by Chōsokabe Kunichika, he adopted his third son, Chikayasu, creating a conflict with Hidemichi. Hidemichi was fiercely opposed to joining forces with Kunichika. In the end, on 10/21 of Kōji 2 (1556), Chikahide ordered his retainers to assassinate Hidemichi.
Chikayasu then became Chikahide’s heir under the name of Kōsokabe Chikayasu, inheriting the headship of the clan. Chikahide continued to support him after retiring. In addition, having regretted the killing of Hidemichi, Chikahide took care of Hidemichi’s eldest son, Yasuyoshi, who adopted the surname of Nakayamada, becoming a chief retainer of the clan known as Nakayamada Yasuyoshi.