Mount Ōyama, Sacred mountain in Kanagawa Prefecture, Japan

Mount Ōyama is a 1,252-metre peak on the border of Isehara, Hadano and Atsugi, at the eastern end of the Tanzawa ridge. It is made of non-alkali mafic rock 7–15 million years old, extruded on the sea floor and later pushed up as the Izu–Bonin–Mariana Arc collided with Honshu. The summit holds the head shrine of Ōyama-Afuri Shrine, built around a large rock as its sacred body; the lower shrine and Ōyama-dera stand on the middle slope.

Mount Ōyama's religious use is documented from the Nara period: the Engishiki shrine register lists Afuri Shrine among the thirteen shrines of Sagami Province, and tradition credits the monk Ryōben with founding Ōyama-dera in 755. In the Edo period, oshi priests organised Ōyama-kō pilgrim groups, and by the early Meiji era the Kōdōki recorded 15,700 such groups with about 700,000 member households. In 1868 the separation of Shinto and Buddhism led to Ōyama-dera's demolition, and the lower Afuri Shrine was built on its site.

The mountain's name Afuri, "rain-falling", comes from the rain and clouds tied to it; farmers prayed at Ōyama-Afuri Shrine to Suijin, god of rain. From the Hōreki era (1751–1764) pilgrimage groups called Ōyama-kō were organised by oshi priests, and Edo townspeople paired a visit here with one to Enoshima. A rakugo comic tale, Ōyama-mairi, takes the pilgrimage as its subject.

From Isehara Station, a bus runs to the cable car base station, where the ride shortens part of the climb while the rest continues on foot along stone paths. The upper section involves open staircases, so sturdy shoes and some stamina help with the steep ascent.

Along the Koma-sando, an old stone stairway, shops line the path offering tofu dishes made from spring water sourced in the Tanzawa range, known for its soft taste. At the upper shrine, visitors throw ceramic plates called kawarake from the cliff, with the belief that a long flight brings good fortune.