Oku-no-in, whose name means 'inner sanctuary', is perhaps the most intensely spiritual place in Japan. At its farthest reaches is the Gobyō, the crypt that Shingon Buddhism founder Kōbō Daishi entered to began his eternal meditation. Spread out before it are some 200,000 tombs, creating Japan's largest cemetery, built during various historical eras by people, prominent and otherwise, who wanted their remains (or at least a lock of hair) interred close to the legendary monk.
Enter the grounds at Ichi-no-hashi, the bridge that marks the entrance to the cemetery, from where it's a 2km walk to the Gobyō. The grounds are thickly forested, sheltering countless five-tiered stupas, many of them worn with age and partly reclaimed by moss. It's a moody place: streaks of sunlight through the trees create enchanting contrast, though so does early-morning mist and, if you can brave the winter cold, blankets of snow.
Gobyō-bashi is the final bridge before the Gobyō. It crosses the Tama-gawa, which runs down from Yōryū-san, the mountain behind the crypt. At this point it's customary to bow, and from here on photographs are prohibited. To the right are the Mizumuke Jizō, bronze effigies that visitors ladle water over as a way of praying for the souls of the departed.
Just past Gobyō-bashi is a wooden building the size of a large phone booth, which contains the Miroku-ishi, a stone said to weigh as much as your sins. Reach through the hole and try to lift it onto the shelf. (Don't feel bad if your sins are too much to handle: most people can't manage the feat.)
Soon you'll encounter the beguiling Tōrō-dō, a large hall full of lanterns, which cover the walls and ceiling. Two of the large ones, in the back of the hall, are said to have been lit uninterruptedly for more than 900 years. Other lanterns have been donated by dignitaries, including emperors and prime ministers. It's here that monks continue to offer food daily to Kōbō Daishi.
Behind the Tōrō-dō is the wooden, thatched-roof gate – humble by contrast – that marks the entry to Gobyō, Kōbō Daishi's mausoleum. This is as far as anyone can go. Pilgrims in a constant stream pause here to light incense and candles and chant sutras.
Oku-no-in is easily reached on foot from the town centre in 10 or 15 minutes, or you can take a bus east to the Ichi-no-hashi-guchi bus stop. On return, you can take a shorter walk down, along the Naka-no-hashi route, which passes more modern tombs and leads you to the Oku-no-in-mae bus stop, where you can catch a bus back to town (or walk it in about 30 minutes).