Jiun Onkō (Jiun Sonja, 1718–1804) was born and raised in Osaka, the son of a masterless samurai and a devoutly Buddhist mother. Forced into the Buddhist clergy at thirteen at the time of his father's death, Jiun became a novice under Ninko Teiki (1671–1750), a master in the Shingon Vinaya sect. This sect stressed both Shingon or Japanese tantric Buddhism and traditional monastic discipline. Under Teiki's influence, and after a period of training in his late teens and early twenties that included Zen and further Confucian studies, Jiun went on to become one of the leading Buddhist scholars and reformers of the Tokugawa period (1603–1868).
Early in his career, Jiun devoted much attention to the study of monastic discipline and the creation of supra-sectarian Buddhist communities that became part of his "Vinaya of the True Dharma" movement. To counteract a moral laxity that he saw in the Buddhist clergy, he advocated a return to what he judged to be a common core of Buddhist thought and practice that he called "Buddhism as it was when the Buddha was alive." Buddhist ethics, the practice of meditation, and, for monks and nuns, the observance of the vinaya or monastic discipline stood at the center of his movement. Jiun's most famous work, Jūzen hōgo (Sermons on the Ten Good Precepts), completed in 1774, was an argument for Buddhist ethics as the foundation of the Buddhist way of life. Jiun is also remembered as one of Japan's greatest Sanskrit scholars. Working without the aid of a Sanskrit teacher and without a living tradition of Sanskrit studies, Jiun compiled the one thousand-chapter Bongaku shinryō (Guide to Sanskrit Studies, 1766) that included information on the geography, history, and customs of India, as well as dictionaries, grammars, and textual studies.
In his later years, Jiun turned his attention to the study of nativism and articulated his own understanding of the positive relationship that existed between Buddhism and Japan's local gods. His interpretation of nativism came to be known as Unden Shintō, or the "Shintō Transmitted by Jiun." When Japan began a period of rapid modernization in the Meiji period (1868–1912), Buddhist leaders who shared Jiun's concerns about the moral laxity of the clergy and the overly sectarian character of Japanese Buddhism drew inspiration from his Sermons on the Ten Good Precepts, and Japanese scholars who were learning of new research on Indian Buddhist languages in Europe looked with pride to Jiun's pioneering Sanskrit studies.
Watt, Paul B. "Sermons on the Precepts and Monastic Life by the Shingon Vinaya Master Jiun (1718–1804)." Eastern Buddhist 25, no. 2 (1992): 119–128.
Watt, Paul B. "Jiun Sonja (1718–1804): A Response to Confucianism within the Context of Buddhist Reform." In Confucianism and Tokugawa Culture, ed. Peter Nosco. Honolulu: University of Hawaii Press, 1997.
Watt, Paul B. "Shingon's Jiun Sonja and His 'Vinaya of the True Dharma' Movement." In Religions of Japan in Practice, ed. George J. Tanabe, Jr. Princeton, NJ: Princeton University Press, 1999.
Paul B. Watt