Chōsa Munemitsu served as a bushō during the Azuchi-Momoyama and early Edo periods. He was a retainer of the Shimazu clan.
The Chōsa were members of the Taira-Hirata clan. In 1560, Munemitsu was born as the son of Chōsa Muneharu.
His father, Muneharu, was a general of the ashigaru, or foot soldiers, under Shimazu Yoshihiro and further served as a military magistrate. Munemitsu also served as a general of the ashigaru under the command of Yoshihiro. In 1582, after Tajiri Akitane of Hizen Province rebelled against Ryūzōji Takanobu and sought help from the Shimazu family, upon orders of Yoshihiro, Munemitsu joined Tajiri Tajima and entered the castle of the Tajiri clan for several months.
Munemitsu joined the advance by Yoshihiro into Bungo Province. After approaching Shimazu Iehisa as a messenger for Yoshihiro, he was retained by Iehisa to serve as a military magistrate. On 12/9 of Tenshō 14 (1586), during an assault against Ogata Castle in Buzen Province, he captured two enemy heads, and, two days later, in battle against the Toyotomi clan, captured five heads. In 1587, at the Battle of Nejirozaka, after Yoshihiro heard that, following a defeat by the Shimazu forces, Ieyasu intended to take his own life, Yoshihiro sent Munemitsu to stop him. Initially, Iehisa did not listen, but after Munemitsu admonished him with the conviction of committing seppuku himself, after a while, Iehisa accepted the plea from Munemitsu not to take his own life.
In 1588, after the Shimazu family received 10,000 koku in Harima Province from Toyotomi Hideyoshi, Munemitsu, together with Ichiki Kamonbei, served as representatives of the family, residing for several years near the capital in Fushimi. In 1590, Munemitsu accompanied Yoshihiro’s second son, Shimazu Hisayasu, to deploy for the Conquest of Odawara, as well as for the Bunroku Campaign on the Korean Peninsula. Munemitsu was appointed to serve as a magistrate for military provisions as well as a construction foreman and distributor of gunpowder.
After returning from Korea, Munemitsu, along with Yoshihiro’s third son, Shimazu Tadatsune, resided in Fushimi. After Tadatsune was murdered by Ijūin Tadamune, Munemitsu served as a secret messenger to notify Shimazu Yoshihisa in Satsuma. In 1599, Munemitsu obeyed Tadatsune to participate in the Shōnai Rebellion in Hyūga Province, providing updates of the situation to Yoshihiro in Fushimi. However, he was kept in Fushimi and then served in the Battle of Sekigahara, later accompanying Yoshihiro to flee to Satsuma after the defeat of the Western Army. Munemitsu received a fief of 100 koku for his efforts.
In 1616, Munemitsu died at the age of fifty-seven.