I could hardly believe, as I settled into the monastic rhythm—a futon and a hard rice-husk pillow had been laid out on the floor while I walked—how far I'd come. At noon, I'd arrived at the entrance to the Koya Line of the Nankai private railway system, in the Namba section of Osaka. On one side of me was a bite-sized McDonald's in which sat a Louis Vuitton girl in a business suit, picking delicately at a Filet-O-Fish, while beside her a young man tried to balance a cell phone, a laptop, and a McFlurry on his small table. Bossa nova music imparted to everything an air of foreign languor. On the other side was a vast underground labyrinth of passageways and staircases that led to a Namba Parks complex of chic Italian restaurants and San Diegan landscaping, a Namba City world of department stores and elegant boutiques. Above us were love hotels and taxis and all the revved-up signs of a modern Japan which believes that to be itself is to be global and generic.

Then, however, I'd passed through the ticket barrier at the station and stepped into a slow-moving country train. Very quickly the featureless, jumbled suburbs of the big industrial city fell away. Concrete gave way to wood, and wood to clustered trees. Green was everywhere, the only gray the rooftops of traditional houses. In ninety-one minutes, the train stopped at fifty-two stations, the platforms themselves emptying out until they were completely deserted, full of the poignancy and nostalgia that the Japanese associate with lonely country stations. It was as if, with each stop, I was less in the company of the bright, chirpy face that Japan is so keen to show the outside world (or maybe even itself) and more in the presence of the Japan that really exists deep down.

The story of Koyasan is a highly detailed one that still shivers on the edge of folktale or creation myth. In the late eighth century, a young Japanese monk called Kukai began studying classic Chinese philosophy and Buddhism in what was then the capital city of Nara, but soon decided that to learn the true secrets of the tradition he would have to go to China itself. In the year 804, at the age of thirty-one, he set sail for Chang'an, the capital of Tang dynasty China and then the largest city in the world, three times the size of the new Japanese capital of Kyoto. In Chang'an, he found a master, and within eight months had himself mastered the mysteries of what is called esoteric, or tantric, Buddhism—which was given the Japanese name Shingon, or "True Word."

Then he sailed back to Japan to try to set up a Shingon training center in some quiet space in his home country. He traveled from place to place, looking for an appropriate site, and ten years later (legend has it), he awoke from a deep meditative trance to find himself in a far-off wilderness. Beside him he saw a hunter, accompanied by one black dog and one white dog. The hunter led him up into the mountains, and there he came upon an area where no human tracks could be seen. More remarkable still, he found the vajra thunderbolt object that he had flung from the beach in China before leaving, to see where it would land in Japan. After petitioning the emperor of the time, he gained permission to build his meditation retreat complex here.