Shugendō (修験道?) is a highly syncretic religion that originated in Heian Japan in which enlightenment is equated with the attainment of oneness with the kami (?), i.e., the spirits or phenomena that are worshiped in the Shinto religion. This perception of experiential "awakening" is obtained through the understanding of the relationship between humanity and nature, centered on an ascetic, mountain-dwelling practice. The focus or goal of Shugendō is the development of spiritual experience and power. Having backgrounds in mountain worship, Shugendō incorporated beliefs or philosophies from early Japanese religious beliefs, Taoism and esoteric Buddhism. The 7th century ascetic and mystic En no Gyōja is often considered as having first organized Shugendō as a doctrine. Shugendō literally means "the path of training and testing" or "the way to spiritual power through discipline."
Shugendō evolved during the 7th century from an amalgamation of several religious influences, including Vajrayana, Shinto, Taoism and Buddhism. Buddhism and Shinto were amalgamated in shinbutsu-shūgō, and Kūkai's syncretic religion held wide sway up until the end of the Edo period, coexisting with indigenous elements within Shugendō.