Shugendo is a colourful blend of Buddhist esoteric and tantric concepts, Chinese Taoist magic and Shinto shamanism. Based on mountain asceticism, the religion was formalized in the eighth century by the monk En-no-Gyoja , who was famous for his mystic powers.

Following Shinto practice, Shugendo's mountain priests, yamabushi , believe that the mountains are centres of sacred power. They go through elaborate initiation rites, austerities and self-denial to acquire this sacred power which they can then use to heal and bless common people. Their practices include meditation, mountain hiking, sitting in smoke-filled rooms, sumo wrestling, and partial denial of food, sleep and daily ablutions. These are designed to train both body and spirit, and are a metaphor for the soul's uncomfortable journey from death to rebirth.

Shugendo was quite popular until the 1868 Meiji Restoration when it, along with other forms of Buddhism, was suppressed. Nevertheless, pockets of this mysterious faith can still be found, notably on Dewa-sanzan in north Honshu where some of the ancient practices survive. One of the most lively events is the Shoreisai (Pine Festival), held on the night of New Year's Eve. Two groups of priests hurl abuse at each other (made all the more colourful by large quantities of sake) and engage in various contests to divine whether the coming year will bring good harvests.