Lifespan: 8/11 of Tenbun 3 (1534) to 7/20 of Keichō 19 (1614)
Other Names: Shichirō (common), Oyama Harutomo
Rank: bushō, sengoku daimyō
Title: Junior Fifth Rank (Lower), Chief of the Left Division of Outer Palace Guards, Vice Minister of Central Affairs
Clan: Oyama → Yūki
Bakufu: Muromachi → Edo
Lord: Toyotomi Hideyoshi → Tokugawa Ieyasu → Tokugawa Hidetada
Father: Oyama Takatomo
Adoptive Father: Yūki Masakatsu
Siblings: Oyama Hidetsuna, Tomioka Hidetaka, Harutomo, sister (formal wife of Edo Shigemichi)
Wife: [Formal] Daughter of Mizunoya Masamura
Children: 陽月貞春大姉 (formal wife of Nasu Sukeharu)
Adopted Children: Tomokatsu (second son of Utsunomiya Hirotsuna), Hidetomo (second son of Tokugawa Ieyasu), Tsuruko (formal wife of Yūki Hideyasu and daughter of Edo Shigemichi)
Yūki Harutomo served as a bushō and sengoku daimyō from the Sengoku to early Edo periods. He was the seventeenth head of the Shimōsa-Yūki clan and served as the lord of Yūki Castle in Shimōsa Province.
On 8/11 of Tenbun 3 (1534), Harutomo was born as the third son of Oyama Takatomo. At his coming-of-age ceremony, he received one of the characters from the name of Ashikaga Haruuji, the fourth Koga kubō, and adopted the name of Harutomo.
In 1556, he participated in the Battle of Ebigashima against the Oda clan, attacking Oda Castle in Hitachi Province. Yūki Masakatsu (Harutomo’s uncle and adoptive father) died in the eighth month of 1559. Masakatsu’s lineal heir, Yūki Akitomo, preceded Masakatsu in death so Harutomo succeeded to the headship of the Yūki clan. Prior to his death, Masakatsu pressured Harutomo to sign a written pledge to cut ties with his natural father, Oyama Takatomo, and deliver it to the messenger for the Koga kubō, Zuiunin Shūkō (who was in fact a representative for the Hōjō clan). In 1560, the Satake cooperated with the Shimotsuke-Utsunomioya and Oda clans to attack with a large army, but Harutomo holed-up in Yūki Castle and repelled them, entering into a settlement. Later that year, upon request of the Satake clan, Nagao Kagetora (later known as Uesugi Kenshin) of Echigo Province undertook an expedition in allegiance to Uesugi Norimasa, the deputy shōgun of the Kantō, but Harutomo continued on the same path as his uncle, Masakatsu, by supporting Ashikaga Yoshiuji (the Koga kubō) and the Gohōjō clan. After Kagetora succeeded Norimasa as the deputy shōgun of the Kantō in the third month of 1561, Harutomo switched sides and opposed the Gohōjō.
In 1570, Harutomo invaded the Oda territory and, at the Battle of Hiratsukahara, violently clashed with Oda Ujiharu. Following the path of Masakatsu, he aimed to revitalize and expand the authority of the Yūki clan. He could not avoid coming into conflict with the Oyama clan (his original home) who, similar to the Yūki, were seeking a means to survive between the Hōjō and the Uesugi. Harutomo frequently clashed on the battlefield with his natural father, Oyama Takatomo. In 1573, even after the death of Takatomo, as the head of the Yūki who were enemies of the Oyama, Harutomo could not rush to visit so, instead, he communicated the news to the abbot of the Jōkoku Temple (the family temple of the Yūki) with whom Takatomo had close ties and had him burn incense to mourn his father.
In 1576, after his older brother, Oyama Hidetsuna, surrendered to Hōjō Ujiteru, in 1577, Harutomo was attacked by the Gohōjō clan. In the twelfth month, Harutomo, who was without an heir at this time, adopted Tomokatsu, the second son of Utsunomiya Hirotsuna, and had his younger sister wed Edo Shigemichi under the command of Satake Yoshishige (the older brother of Tomokatsu’s mother). Meanwhile, Nasu Suketane had his daughter wed the eldest son and lineal heir of Yoshishige, Tokujumaru (later known as Satake Yoshinobu). Based on political alliances forged through these marriages, Harutomo allied with neighboring lords to withstand the attacks by the Hōjō.
Later, he followed Toyotomi Hideyoshi and, in 1590, participated in the Conquest of Odawara for which he received recognition of his rights to his territory. From around the time that Harutomo obeyed Hideyoshi, he made a request via Mizunoya Katsutoshi to establish a relationship with the Toyotomi through adoption whereupon he had his adopted daughter, Tsuruko, wed Hideyasu (the second son of Tokugawa Ieyasu adopted by Hideyoshi) and received Hideyasu as his adopted heir. Hideyasu received one of the characters from the name of Harutomo and changed his name to Hidetomo. Harutomo then transferred headship of the clan to him and retired. At this time, however, it is surmised that Harutomo had already retired after transferring headship of the clan to Tomokatsu. From the beginning of 1587 until the fourth month of 1590, no records have been founds regarding the lands, titles, or honorary names of the Yūki clan that display Harutomo’s seal. In the fifth month of 1590, Harutomo captured Enomoto and Oyama castles defended by Oyama Hidetsuna who was aligned with the Hōjō. Harukatsu, together with his older brother, Utsunomiya Kunitsuna, participated under Hideyoshi so, during this period, Harutomo temporarily reverted to the role as the head of the Yūki clan while Tomokatsu returned to his original home with the Utsunomiya family.
In 1604, Harutomo followed Hideyasu after a transfer to Echizen Province. From around this time, Hideyasu and others around him sought to revert to the Tokugawa clan. Hideyasu died in 1607 and was succeeded by his eldest son and lineal heir, Tadanao who adopted the Matsudaira surname. Until cutting ties with his natural father (Oyama Takatomo) and adopted son (Yūki Tomokatsu), Harutomo bore the shock of losing the landholdings and family name of the Yūki dating back to the Kamakura period which he had endeavored to protect. After his entreaty to Tokugawa Ieyasu, he raised Naomoto, the fifth son of Hideyasu and had him inherit the Yūki family. While requesting to return to the former territories of the Yūki, he compiled the genealogies, death records, and accounts of the family and provided them to shrines and temples having connections to the Yūki.
On 7/20 of Keichō 19 (1614), Harutomo died in either Kita-no-shō in Echizen or Nakakuki Castle in Shimotsuke at the age of eighty. His territory was inherited by Naomoto. Upon the death of Harutomo, the bloodline of the Yūki came to an end but successive generations of the Maebashi-Matsudaira family who were descendants of Naomoto inherited the rituals of the Yūki clan.
The ruins of Nakakuki Castle where he is said to have died are traversed by the JR-Mito rail line which is not evident when seen from a distance.