Monks at morning prayer, Senshu-Gakuin temple, Koya-san, Japan. Koya-san, a holy mountain south of Osaka, is Japan's principal centre of the esoteric Shingon ('True Word') school of Buddhism, founded in 816 AD by the monk Kukai (also known as Kobo-Daishi). In Shingon Buddhism, all deities, including the kami spirits worshipped in Shinto, are considered emanations of the supreme Buddha-nature.