Oomoto (大本 Ōmoto?, Great Source, or Great Origin), also known as Oomoto-kyo (大本教 Ōmoto-kyō?), is a sect founded in 1892 by Deguchi Nao (1836–1918), often categorised as a new Japanese religion originated from Shinto. The spiritual leaders of the movement have predominantly been women; however, Deguchi Onisaburō (1871–1948) has been considered an important figure in Omoto as a seishi (spiritual teacher). Since 2001, the movement has been guided by its fifth leader, Kurenai Deguchi.
Deguchi Nao, a housewife from the tiny town of Ayabe, Kyoto Prefecture, declared that she had a "spirit dream" at the Japanese New Year in 1892, becoming possessed (kamigakari) by Ushitora no Konjin and starting to transmit his words. According to the official Oomoto biography of Deguchi, she came from a family which had long been in poverty, and had pawned nearly all of her possessions to feed her children and invalid husband. Deguchi was certainly not an otherwise famous figure, and independent accounts of her do not exist. After 1895, and with a growing number of followers, she became a teacher of the Konkōkyō religion. In 1898 she met Ueda Kisaburō who had previous studies in kamigakari (spirit possession), and in 1899 they established the Kinmeikai, which became the Kinmei Reigakkai later in the same year. In 1900 Kisaburō married Nao’s fifth daughter Sumi and adopted the name Deguchi Onisaburō. Omoto was thus established based on Nao's automatic writings (Ofudesaki) and Onisaburō’s spiritual techniques.