Hyūga Province
Harunori was the younger son of Akizuki Tanemitsu, "daimyō" of Takanabe Domain in Hyūga Province. His mother was a granddaughter of the fourth "daimyō" of Yonezawa Domain, Uesugi Tsunanori.His childhood names were "Matsusaburō" (松三郎) and "Naomatsu" (直松). His mother died when he was very young, and is was large raised by his grandmother, which strengthened his ties to Yonezawa. At age ten he was adopted by Uesugi Shigesada, then "daimyō" of Yonezawa, who had a daughter but no male heir. After arriving in Yonezawa, from 1763 he became an ardent disciple of the Neo-Confucian scholar Hosoi Heishu, whose teaching would strongly influence his political philosophy and governing outlook. In 1766, he underwent the genpuku ceremony and received the "kanji" of "Haru" in his name from Shogun Tokugawa Ieharu as a sign of special favor. In 1767, he became "daimyō" of Yonezawa.