Lifespan: Eishō 1 (1504) to 6/15 of Eiroku 3 (1560)
Rank: bushō, daimyō
Title (Informal): Governor of Shinano, Assistant Vice Minister of the Sovereign’s Household
Father: Chōsokabe Kanetsugu
Siblings: Kunichika, Kuniyasu, Chikayoshi, sister (wife of Yoshida Takayori), Riharu-ni (wife of Kataoka Shigeaki)
Wife: [Formal] Shōhō
Children: Motochika, Kira Chikasada, Kōsokabe Chikayasu, Shima Chikamasu, Motoyama Fujin (wife of Motoyama Shigetoki), daughter (wife of Ike Yorikazu), Yōho-ni (wife of Hakawa Kiyomune)
Chōsokabe Kunichika served as a bushō and daimyō during the Sengoku period. Kunichika endeavored to revive the Chōsokabe clan.
In 1504, Kunichika was born as the eldest son of Chōsokabe Kanetsugu. His childhood name was Senyūmaru.
Under traditional theory, in 1508, Kunichika’s father, Kanetsugu, was attacked by the Motoyama clan and took his own life in his base at Okō Castle, whereupon Kunichika fled and was raised by a noble and daimyō named Ichijō Fusaie (the second head of the Ichijō clan in Tosa). In 1518, through the offices of Fusaie, Kunichika returned to the townships of Emura and Hataeda and reclaimed Okō Castle. Thereafter, he endeavored for the revival of the Chōsokabe family. Based on recent research, however, at the time of the attack on Okō Castle, Kanetsugu did not take his own life and, instead, took refuge within the province. In 1511, he reconciled with the Motoyama and Yamada clans and returned to his position as the lord of Okō Castle. Around 1518, he transferred headship of the clan to his eldest son, Kunichika.
He received one of the characters from the name of Hosokawa Takakuni (the military governor of Tosa and deputy shōgun of the Muromachi bakufu), adopting the name of Kunichika. His younger brother, Chōsokabe Kuniyasu, also received one of the characters in his name from Takakuni.
Kunichika appointed Yoshida Kanetaka to manage internal affairs and furthered military preparations. In 1544, he arranged for his daughter to wed Motoyama Shigetoki, the eldest son of Kunichika’s former archenemy, Motoyama Shigemune.
In 1547, Kunichika attacked neighboring Ōtsu Castle, decimating the Tenjiku clan. In Kera to the south of Ōtsu, he subdued the Yokoyama clan and killed Shimoda Suruga-no-kami, a renowned bushō, en route to capturing Shimoda Castle. Next, he forced the surrender of Hosokawa Sadasuke of the Tōichi-Hosokawa clan and arranged for his daughter to wed Sadasuke’s second son, Hosokawa Ikeyori, to ensure their allegiance. In this way, Kunichika took control of the southern portion of the Nagaoka District. Kunichika’s expansion of power stirred concerns among neighboring landlords leading to the surrender of landlords in Nunoshida and Ichinomiya so he also garnered control of the southwest portion of the Tosa District. In the autumn of 1549, Kunichika eliminated the Yamada clan, archenemies who had earlier defeated his father. In 1556, he sent his third son, Chikayasu, for adoption as the designated heir to the Kōsokabe clan under the name of Kōsokabe Chikayasu, bringing them under his control. While causing the submission of the kokujin, or provincial landowners, of Tosa, Kunichika attained control of the plains of central Tosa. Toward the end of the Tenbun era (1532 to 1555), Kunichika underwent the rites of tonsure and adopted the monk’s name of Zuiō Kakusei.
In 1555, Motoyama Shigemune died of illness. Shigemune was succeeded by Kunichika’s son-in-law, Motoyama Shigetoki, based at Asakura Castle in the central plains area. Shigetoki continued to oppose Ichijō Kanesada and, on 2/25, toppled Hasuike Castle in the Takaoka District. In 1556, however, Kunichika raised arms so Shigetoki came into conflict with Kunichika and Kunichika’s son, Motochika. That same year, Kunichika forced the surrender of the Jinzenji clan who were retainers of the Motoyama, and then proceeded to eliminate the Ōdakasa and Kunisawa clans. A vessel heading from Okō to Tanezaki to bring military provisions to the Chōsokabe was attacked en route by two vessels aligned with the Motoyama from Shioie and the cargo taken. Seeking to avenge the loss, Kunichika persuaded a former retainer who had sided with the Motoyama named Fukudome Sama-no-jō (a well-known builder) to open the gates of Nagahama Castle. On 5/26, Kunichika then launched a nighttime attack and captured the castle. In an event known as the Battle of Nagahama, on 5/27, Shigetoki summoned 2,000 troops to Asakura Castle for the purpose of retaking Nagahama Castle, but, owing to valiant efforts by 1,000 fighters under the command of Kunichika, Shigetoki suffered a major defeat.
In the sixth month, Shigetoki lost Urado Castle and holed-up in Asakura Castle. Thereafter, the outlying castles intended to support Asakura Castle fell to the Chōsokabe and, in the third month of 1561, he was attacked and defeated.
Soon thereafter, on 6/15 of Eiroku 3 (1560), Kunichika suddenly died of illness. He was fifty-seven years old. The headship of the clan was inherited by his eldest son, Chōsokabe Motochika.
Similar to the actions of Mōri Motonari of Aki Province with respect to the Kikkawa and Kobayakawa clans, the Chōsokabe brought under their command the Kōsokabe, a member of the kunishū of Tosa, by having them adopt one of their sons as the heir to their clan. After inheriting the clan, Chōsokabe Motochika also brought under his command the Kira clan by the same means. Kunichika conceived the military structure of the Chōsokabe clan known as ichiryō-gusoku that was comprised of jizamurai, or local samurai, and armed peasants who split their time between military service and farming prior to the period when these occupations were separated.