Mount Gassan — 月山

Mount Gassan is the only mountain shrine in Japan that remains completely buried under snow for half the year. The summit shrine, at 1,984 meters, closes in October and does not reopen until July — not because of policy, but because it becomes physically inaccessible, locked beneath five meters of snow that turns the peak into a white void. When pilgrims finally arrive at the shrine in summer, they are required to walk across the snow that entombed it, wearing white robes of ritual death and rebirth. Gassan is considered the realm of the dead, the moon mountain, where souls linger before moving on.

Mount Gassan was opened as a sacred peak in 593 CE by Prince Hachiko, who is said to have encountered a three-legged crow — the divine messenger — during meditation on the summit. The shrine became the centerpiece of Dewa Sanzan, the three sacred mountains of Yamagata Prefecture, alongside Mount Haguro and Mount Yudono. For over a thousand years, Gassan has functioned as the afterlife mountain in this triad cosmology: Haguro represents birth and the present world, Gassan represents death and the ancestral realm, and Yudono represents rebirth. During the Edo period, the pilgrimage route saw tens of thousands of white-robed pilgrims annually, many walking barefoot in the snow. The current shrine structure dates to the Meiji period, rebuilt after a catastrophic avalanche destroyed the previous buildings in 1892.

Tsukuyomi no Mikoto is the primary deity of Mount Gassan — the moon god and ruler of the night realm in Japanese mythology. Tsukuyomi is one of the three noble children born from Izanagi’s purification ritual: Amaterasu governs the sun and day, Susanoo governs the sea and storms, and Tsukuyomi governs the moon and the boundary between life and death. Unlike his siblings, Tsukuyomi rarely appears in myth after his creation, dwelling in silence and absence. This makes Gassan uniquely somber among Japan’s mountain shrines — it is not a place of vitality or agricultural blessing, but of stillness, reflection, and communion with ancestors. Pilgrims come to Gassan to honor the dead and to symbolically die and be reborn through the ascent.

The shrine’s founding legend tells of Prince Hachiko’s encounter with the Yatagarasu, the three-legged crow of the sun goddess, which appeared to him on Gassan’s summit despite the mountain being sacred to the moon. The crow revealed that the mountain was a threshold — a place where the solar world and lunar world touched, where the living could meet the dead without crossing over entirely. In another legend, a monk named Kūkai (not the famous founder of Shingon Buddhism, but a local ascetic) spent an entire winter buried in a snow cave on Gassan in the 9th century, emerging in spring with white hair and the ability to see spirits. The mountain’s association with death is also tied to the Nihon Shoki account of Tsukuyomi’s estrangement from Amaterasu: after killing the food goddess Ukemochi, Tsukuyomi was banished from the sun’s presence, condemned to rule the night in separation. Gassan embodies this exile — a shrine perpetually half in darkness, half in snow.

The summit shrine is a small wooden structure rebuilt in traditional nagare-zukuri style, designed to withstand extreme weather. The shrine building sits at the very peak, surrounded by alpine grassland that blooms with wildflowers for only two months each summer. The approach to the summit requires a four-hour hike from the Eighth Station, passing through fields of residual snow even in August. Pilgrims must rent white robes at the base and carry bells to ward off bears. At the summit, there is a small haiden (worship hall) and a sacred mirror rather than a typical statue or object of worship — reflecting the moon’s own reflective nature. The Eighth Station, where most ascents begin, contains the shrine office, lodgings, and a purification hall where pilgrims undergo ritual cleansing before the climb. In winter, the entire summit vanishes beneath snow, and the shrine becomes conceptually buried — a physical enactment of death.

• Opening of the Mountain (July 1) — The shrine reopens after eight months of closure, marked by a ceremony where priests ascend through snow to unlock the shrine and replace offerings. Pilgrims follow in white robes.
• Hassaku Festival (August 1) — The peak pilgrimage day, when hundreds climb at dawn to witness sunrise from the summit, symbolizing the soul’s return to light after dwelling in the lunar realm.
• Closing Ceremony (Late September) — Priests perform final rites and seal the shrine before the first heavy snows arrive, bidding farewell to the mountain until summer.
• Moonlit Pilgrimage — On full moon nights in summer, small groups make night ascents, walking by moonlight in homage to Tsukuyomi, arriving at the summit at dawn.

August, when the alpine flowers bloom and the snow has receded enough for safer passage. The mountain is only accessible from early July through late September, but July still requires navigating deep snowfields. August offers the clearest skies, though this also brings the largest crowds. For solitude, attempt the ascent on a weekday in mid-September, when autumn colors begin to touch the lower slopes and the first cold winds carry the scent of approaching closure. Sunrise from the summit is essential — the moment when Tsukuyomi’s realm yields to Amaterasu’s light.