Born in 1534, Harutomo was the 17th head of the Shimousa Yuki clan, based at Yuki Castle, and worked to preserve his house amid the shifting powers of Shimotsuke and Hitachi. Having no son of his own, he petitioned Toyotomi Hideyoshi during the 1590 Odawara Campaign to adopt Tokugawa Ieyasu's second son Hideyasu (later Yuki Hideyasu) as his heir, making him the 18th head of the Yuki clan. Harutomo then handed over the headship and retired to Nakakuki Castle (also called Toroi Castle) in Oyama, Shimotsuke, where he spent the following years. After Ieyasu's victory at the Battle of Sekigahara in 1600, Hideyasu was rewarded with a transfer from Yuki's 100,000 koku to the much larger 670,000-koku domain of Kitanosho in Echizen; Harutomo and much of the retainer band left Yuki in 1601. He died in 1614 at the age of 80.

A shrewd political strategist who, facing the survival of his heirless house, made the bold move of petitioning Hideyoshi directly to secure Ieyasu's own son as his heir.

By bringing Tokugawa blood into the Yuki line, he laid the foundation for the Echizen Matsudaira house descended from Yuki Hideyasu. Nakakuki Castle, where he retired, is today part of the "Oyama Clan Castle Ruins" National Historic Site.