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Fuji-Hakone-Izu NP, Yamanashi
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For Fujiko pilgrims, this was a rebirth chamber: they crawled through the cave the day before climbing Fuji to purify themselves, then returned to their hosts’ homes to prepare for the ascent.
This is a cluster, not a lone cave: the 10th-century Kenmarubi lava flow left 43 tree molds here. Several neighboring trunks formed the largest, roughly 70-meter-long passage.
After crawling out, pilgrims drank seaweed soup—the kind traditionally fed to infants. This unusual post-crawl food custom fits the cave’s powerful theme of birth and renewal.
Pregnant women once soaked sash cords in the cave’s dripping water, nicknamed its “milk,” and burned leftover pilgrimage candles as charms for safe childbirth.
The cave has sections called the “Father’s Womb” and “Mother’s Womb.” The shrine associates them with Ninigi-no-Mikoto and Fuji’s goddess Konohanasakuya-hime, respectively.
Pilgrims wore special straw sandals reaching to their knees as they crawled through the passage. It was a strikingly practical detail of a journey meant to purify them before climbing Fuji.
Local accounts say Hasegawa Kakugyo enshrined a small tree mold here by 1617; in 1673, Murakami Kosei established worship at the largest mold and built a shrine near its entrance.
A large shrine-side monument records the naming of the passage “Tainai-kuguri” in 1772. More than 800 names are carved on its reverse—a remarkable roll call of Fuji pilgrims.
Pilgrims also prayed to small images of Dainichi and Kannon inside the cave. Their presence beneath today’s Sengen shrine recalls the mingling of Buddhist and kami worship at Fuji.
Visitors can still crawl through the same passage pilgrims used. The old route now has electric lighting and safety helmets, but the journey through Fuji’s “womb” remains wonderfully hands-on.
