Futarasan is not a single building but a sprawling spiritual geography. The main shrine sits in Nikko's sacred precinct, tucked between the famous Toshogu mausoleum and the Taiyu-in, surrounded by the ancient cryptomeria forests that make this valley feel permanently dusk. The middle shrine stands on the shore of Lake Chuzenji, a crater lake formed by the eruptions of Mount Nantai. It was built in 1096 and its current buildings date to a 1699 reconstruction. The innermost shrine, the Oku-no-miya, perches at the summit of Mount Nantai itself -- the volcano that dominates the Nikko skyline at 2,486 meters. It was founded in 782. Archaeologists excavating the summit have recovered ritual instruments from the Nara period, confirming that people have been climbing this mountain to pray for over 1,200 years. Together, the shrine's precincts encompass 3,400 hectares, including eight mountain peaks and the thundering Kegon Falls -- an area second in size only to the Ise Grand Shrine.

Long before Shodo Shonin arrived, Mount Nantai was already sacred. The mountain had been worshipped since at least the Yayoi period as a shintaizan -- a mountain that serves as a yorishiro, a vessel housing a kami, a divine spirit. The reason was practical as much as spiritual: Nantai's snowmelt and rainfall fed the streams that watered the plains below, where people grew rice and sustained their families. The mountain gave life, and so the mountain was divine. This ancient mountain cult eventually merged with Shugendo, a syncretic tradition blending Shinto animism with esoteric Buddhism, creating a practice of mountain asceticism that treated the physical act of climbing as a form of prayer. Shodo's founding of Futarasan Shrine in 767 formalized this worship. The kami enshrined there govern nation-building, agriculture, medicine, and thunder -- domains that trace directly back to the mountain's role as the source of water and therefore survival.

The shrine's history tracks the turbulence of Japan itself. During the Sengoku period, the era of warring states, powerful clans stripped Futarasan of its landed estates. The Late Hojo clan seized its properties, and Toyotomi Hideyoshi took what remained. But the Tokugawa shoguns, who chose Nikko as their spiritual capital, rebuilt everything. Tokugawa Hidetada reconstructed the shrine in 1617, and the buildings standing today date from that restoration. Powerful daimyo and members of the nobility poured support into the shrine, tying its fortunes to the shogunate's prestige. When the Meiji government reorganized Shinto into a state system in 1871, Futarasan received one of the highest rankings. In 1998, its grounds were designated a National Historic Site as part of the Shrines and Temples of Nikko. The following year, 1999, that designation expanded to UNESCO World Heritage status. The shrine possesses two swords classified as National Treasures of Japan, and dozens of buildings and artifacts carry Important Cultural Property designations.

Futarasan's grounds hold artifacts that blur the line between devotion and folklore. Among them is the Bake-doro, the so-called Ghost Lantern -- a Chinese-style bronze lantern in the shrine precinct that, according to tradition, was slashed by a samurai guard who mistook its flickering light for a supernatural apparition. The cuts in the metal are still visible. The Shinkyo bridge at the shrine's entrance remains the most photographed structure in Nikko. Its vermilion lacquer glows against the dark green of the river gorge, and on clear days the reflection doubles the arch into a perfect circle on the water's surface. The bridge was registered as a World Heritage structure in December 1999. Standing on it, with the sound of the Daiya rushing below and the cedar canopy closing overhead, you are standing where legend says two serpents became a rainbow. Futarasan specializes in that kind of moment -- where the physical world and the mythic one become briefly indistinguishable.