Lifespan: 14xx to Unknown
Other Names: Sasaki Kosaburō
Rank: bushō, shugo daimyō
Lord: Ashikaga Yoshitaka
Father: Yamauchi Masatsuna
Yamauchi Naritsuna served as a bushō and shugo daimyō during the late-Muromachi period. Later, he became the head of the Rokkaku clan and was appointed the military governor of Ōmi Province.
The Yamauchi were a branch of the Rokkaku, members of the Sasaki clan descended from the Ōmi-Genji. Naritsuna was born as the son of Yamauchi Masatsuna, a senior retainer of the Rokkaku clan.
The Yamauchi were powerful relatives of the Rokkaku clan. In the era of Yamauchi Nobunori, after Rokkaku Ujiyori absconded in 1351, Nobunori looked after a youthful Rokkaku Yoshinobu, a shugo daimyō, military governor of Ōmi, and the fifth head of the Rokkaku clan. Naritsuna’s father, Masatsuna, also looked after a young Rokkaku Yukitaka (later known as Rokkaku Takayori). From 1467, during the Ōnin-Bunmei War, he sided with the Western Army and fought valiantly. Yukitaka, however, did not return the territory earlier seized and allocated to the kokujin, or provincial landowners, in Ōmi so, beginning in the eighth month of 1491, he was subject to a campaign led by Ashikaga Yoshiki, the tenth shōgun of the Muromachi bakufu, to eliminate him in the second phase of the Chōkyō-Entoku Expedition. In the twelfth month, he abandoned his base, traversed the mountains of Kōka, and fled in defeat to Ise Province. Yoshiki planned to back as the new military governor the adopted son of Rokkaku Masataka named Torachiyo or Hachirō, the son of Takashima Etchū-no-kami from the Takashima clan.
In the fourth month of 1493, Yoshiki was deposed in a coup d’ètat known as the Meiō Political Incident. In the wake of this incident, in the tenth month, Rokkaku Torachiyo who was appointed by Yoshiki was removed while Naritsuna became the head of the Rokkaku clan and was appointed by Yoshiki’s successor, Ashikaga Yoshizumi, to serve as the military governor of Ōmi. Taking advantage of the turmoil, Rokkaku Yukitaka stirred an uprising. Naritsuna, together with followers of the Enryaku Temple, fought against Yukitaka. In the twelfth month, Yukitaka, with the support of Saitō Myōjun, the deputy military governor of Mino Province, defeated Naritsuna who then retreated to Sakamoto in Ōmi.
In the third month of 1495, Naritsuna departed from Ōmi and stayed in Kyōto. Later that year, Ashikaga Yoshitaka appointed Rokkaku Yukitaka as the military governor of Ōmi.