Oka-son Kuroki was from Omi. His name was Zai, his azana was Shiatsu, and he called himself Kuroki. He went to Kyoto and became a disciple and adopted son of Oka-son Kisai (1815-1873, a Confucian scholar who was a feudal retainer of the Hagi clan and studied under Yamagata Bokusen and Maki Hyakuhō, and served as a professor at the clan school Meirin-kan). After returning to Yamaguchi and running a private school called Keishi-juku, he became the principal of Yamaguchi First Elementary School. Later, while teaching at Yamaguchi Normal School, he founded Kuroki-juku. He was a calligrapher and a scholar of Chinese classics, and it is said that his students numbered in the thousands.