Lifespan: Tenbun 7 (1538) to 10/8 of Tenshō 10 (1582)
Title: Assistant Director of the Bureau of Palace Maintenance, Governor of Sanuki
Clan: Hosokawa (family of the military governor of Awa Province)
Father: Hosokawa Mochitaka
Siblings: Saneyuki, Miyoshi Nagaharu, Sogō Masayasu, Chōsokabe Ukon Taifu (?) (all were younger brothers of a different father)
Children: Takayuki, Nobuyuki, Hatakeyama Yukiteru
Hosokawa Saneyuki served as a bushō during the Sengoku and Azuchi-Momoyama periods. Saneyuki served as the tenth head of the Hosokawa family serving as military governors of Awa Province in Shikoku.
His common names were Rokurō and Kamon-no-kami. His mother was Koshōshō, while Miyoshi Nagaharu, Sogō Masayasu, and Chōsokabe Ukon Taifu were younger brothers of a different father.
In 1538, Saneyuki was born as the son of Hosokawa Mochitaka, the military governor of Awa.
In 1553, after Mochitaka was murdered by Miyoshi Jikkyū, Saneyuki was backed in a puppet administration. After the death of Jikkyū in 1562, Saneyuki was used again as a puppet, this time by Jikkyū’s son, Miyoshi Nagaharu. Saneyuki became very dissatisfied with the situation so, around 1577, he fled from Shōzui Castle and, with the assistance of Fukura Tsuratsune, went into the Niu mountains in the Naka District of Awa to plan for a revival. He then joined with Ogasawara Narisuke, who shared Saneyuki’s resentment toward Nagaharu, to request the support of the Chōsokabe clan of Tosa Province and eliminate Nagaharu at a battle in Aratano in Awa. On 3/28 of Tenshō 5 (1577), Nagaharu was killed in this clash at the age of twenty-five.
This gave rise to opposition by individuals including Miyoshi Echigo-no-kami, Yano Kunimura, and Kawamura Sama-no-jō, who backed Sogō Masayasu (a member of the Miyoshi clan who inherited the Sogō clan of neighboring Sanuki Province) and welcomed him to Shōzui Castle. In 1579, owing to events such as the removal of a powerful kokujin aligned with the Hosokawa named Izawa Yoritoshi, Saneyuki confronted a deteriorating situation. Meanwhile, after allying with Oda Nobunaga, Chōsokabe Motochika of Tosa prioritized his conflict against the Miyoshi in Awa. When the Oda came to the support of the Miyoshi, Motochika became an enemy of the Oda clan and was exposed to the threat of the invasion of Shikoku by the Oda army. Nevertheless, after the unexpected death of Oda Nobunaga in the Honnō Temple Incident on 6/2 of Tenshō 10 (1582), Masayasu lost his patron and, just two months later, in the eighth month, Motochika invaded Awa Province. At the ensuing Battle of Nakatomigawa, Masayasu lost Shōzui Castle which had served as his base for governing the province and was compelled to retreat to Toramaru Castle in Sanuki Province.
In the tenth month, Sogō Masayasu invaded Awa again, and had several hundred troops including Emura Jirō Taifu, Motoki Shinzaemon, Tsuyuguchi Hyōgo, and Emura Hei-no-jō attack Saneyuki at Ibaragaoka Castle. Defeated, Saneyuki proceeded to take his own life on the Hachiman Plains on 10/8 and the Awa-Hosokawa family came to an end. Questions remain concerning the date of Saneyuki’s death after the withdrawal to Sanuki by Masayasu in the wake of his defeat at the Battle of Nakatomigawa as well as details of the second invasion of Awa by the Sogō army after their defeat and the subsequent attack on Ibaragaoka Castle. Moreover, beginning on 8/11 until the winter season of 1582, the combined forces of the Chōsokabe and Kagawa armies laid siege to Sogō Castle in an event known as the First Siege of Sogō Castle. Based on a reference to Emura Hei-no-jō and others involved in the attack as traitors from the mountains, there is a theory that these individuals were kokujin in Awa abiding by Saneyuki until that time, while the purge of former elements by Chōsokabe Motochika is also noted.