Lifespan: Eishō 17 (1520) (?) to Tenshō 1 (1573)
Name Changes: Naohiro → Haruhiro → Harutsuna
Title: Master of the Eastern Capital Office
Father: Yūki Yoshitsuna
Siblings: Tōnosuke (?), Harutsuna, Komine Yoshichika (?)
Children: Nakahata Harutsune, Yoshiaki, Kobari Yorihiro, Komine Yoshichika (?)
Yūki Harutsuna served as a bushō during the Sengoku and Azuchi-Momoyama periods. He was the tenth head of the Shirakawa-Yūki clan.
Harutsuna was born as the lineal heir of Yūki Yoshitsuna, the ninth head of the Shirakawa-Yūki clan.
Initially, he was known under the name of Naohiro and, kin 1542, was invested with the title of Master of the Imperial Guards of the Left Division. At the same time, he received one of the characters from the name of the Koga kubō, Ashikaga Haruuji, and adopted the name of Haruhiro. The next year, he changed his name again to Harutsuna. This appears to be around the time that Yoshitsuna transferred headship of the Shirakawa-Yūki clan to him.
Harutsuna engaged in ongoing battles against the neighboring Nikaidō clan as well as the Tamura and Ishikawa clans. While maintaining friendly relations with the Iwaki clan, benefiting from their mediation in numerous disputes with the Satake clan.
There are no clear traces in historical records to indicate that Harutsuna actively participated in an internal dispute for control of the Date clan known as the Tenbun Conflict. Nevertheless, in 1545, Date Harumune sought to forge friendly relations with Harutsuna and, that same year, Harutsuna encroached on the territory of Nikaidō Teruyuki. In 1546, Harumune appealed to Harutsuna to keep in check Tamura Yoshiaki and Tamura Takaaki (father and son) from the rear, suggesting Harutsuna was aligned with Harumune during the Tenbun Conflict. Meanwhile, he also appears to have cultivated friendly relations with Date Tanemune.
In 1539, when Nasu Masasuke and Nasu Takasuke (father and son) of Shimotsuke Province quarreled, Harutsuna cooperated with Yūki Masakatsu and Oyama Takatomo of the Shimōsa-Yūki clan in support of Takasuke.
In 1551, Harutsuna collaborated with Nihonmatsu Yoshikuni to mediate a settlement between the Ashina and Tamura clans. After overcoming internal discord, in 1555, Harutsuna sought to prevent the Satake clan from invading his territory whereupon he allied with the Ashina clan by arranging for Komine Yoshichika (the head of families who were members of the clan) wed the daughter of Ashina Moriuji. He also exchanged letters to cultivate relations with the Hōjō of Odawara for support in the conflict with the Satake. In 1560, however, another conflict erupted with the Nasu clan triggering the Battle of Odakura. This resulted in a gradual decline in the power of the Shirakawa-Yūki.
Under the governance of Harutsuna, as before, the northern advance of the Satake clan could not be halted. Satake Yoshiaki took control of Terayama Castle in 1560 and Hagurosan Castle in 1564. In 1574, Yoshiaki’s successor, Satake Yoshishige, toppled Akadate Castle. In addition, the Nangō area came entirely under the control of the Satake clan.
In his later years, Harutsuna lost his sight and lay ill. His lineal heir, Yūki Yoshiaki, was still in his youth so Komine Yoshichika led the affairs of the Shirakawa-Yūki.