This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Onisaburo Deguchi married into Deguchi Nao's family in 1900 and became Omoto's principal early leader and doctrinal architect, organizing Nao's Ofudesaki into a systematic cosmology and building the movement's institutions, publishing empire and mass following, which by the late 1920s and early 1930s the historian Nancy Stalker estimates reached over two million believers, a scale that made Omoto one of interwar Japan's most consequential new religious movements.
Beginning in 1921 he dictated the Reikai Monogatari, an eighty one volume account of the spirit world, the creation of the universe and the coming reconstruction of a divine kingdom, composed across two periods either side of Omoto's first suppression by the imperial Japanese state that same year, so the work's composition was itself interrupted by the persecution its content responded to.
His student Morihei Ueshiba, founder of aikido, drew the art's religious purpose directly from Omoto cosmology under Onisaburo's influence, meaning Onisaburo's doctrinal system reached a global martial art audience that has never necessarily known its Omoto origin.