In 1558, Kagemitsu assumed the role of gunji, or district governor, for the Tsuruga District in Echizen previously held by his father. In 1561, Kagemitsu participated in suppressing a rebellion by the Hemi clan based on a request from the Takeda clan in neighboring Wakasa Province. In 1563, he was deployed with his father, Kagetoshi, to attack Awaya Katsuhisa, a rebellious retainer of the Takeda in Wakasa. In 1564, Asakura Yoshikage made a decision to invade Kaga Province, appointing Asakura Kageakira and Asakura Kagetaka to serve as the commanding generals. The Asakura army entered Kaga in the early autumn. At this time, Kagemitsu sought to command the forces but he was refused by Yoshikage, the eleventh lineal head of the clan.
The day after the invasion, Kagemitsu argued with Kageakira, and, having lost, took his own life. It was unusual for commanding officers or family members of the clan to take their own lives during a deployment, causing Yoshikage himself to quickly deploy and assume the role of commanding general. He successfully directed the battle. The incident concerning Kagemitsu resulted in a decisive break in relations between Kagetoshi (governor of the Tsuruga District) and Kageakira (governor of the Ōno District). This falling out was ultimately one of the contributing factors to the demise of the Asakura clan.
Kagemitsu’s son, Shichirō, was only two years old at the time that Kagemitsu took his own life. Kagetoshi’s second son, 松林院鷹瑳, left a monastery to return to secular life, adopt the name of Asakura Kagetsune, and become the governor of the Tsuruga District. Shichirō moved with Kagetoshi to his place of retirement in the Yoshida District of Echizen, but, afterwards returned to Tsuruga. His whereabouts became unknown after the demise of Yoshikage.