Kobo Daishi Kukai opened Koyasan for Shingon Esoteric Buddhism at the start of the Heian period. One hundred and seventeen temples stand on the mountain today, fifty-one of them shukubo lodgings that take guests overnight, and the temple that directs the religious affairs of the whole school is Kongobuji. It is one of the component parts of the World Heritage property Sacred Sites and Pilgrimage Routes in the Kii Mountain Range.
Buy an admission ticket and you are already inside; there is no threshold here. The weight is in what you meet once you are through the door. On the sliding screens of the Ohiroma, the great hall, a pine and a crane are painted; further in, the Yanagi no Ma has its willow and heron, and that room carries a second name: the room where Hidetsugu took his own life. Toyotomi Hidetsugu ended his life in it. You stand behind a low wooden rail with the painting at eye level and the act under your feet, and the guide does not need to raise their voice.
Beyond it lies Banryutei: about 2,340 square meters, some 707 tsubo, one of the largest rock gardens in Japan. White sand stands for a sea of cloud and granite for a pair of dragons set face to face, guarding the Okuden at the center. It is large enough that from the veranda you measure it with your eyes first and decide afterwards whether to say anything at all.
What is genuinely scarce is not getting in; it is taking the whole of it for one evening. Kongobuji publishes no window for exclusive event use: the Ohiroma or Banryutei as a venue appears on no page anyone can click to book, so it can only be raised separately, and it may well come to nothing. By day this is the center of a sacred mountain that anyone may visit; the exclusive evening is the one that begins after everyone else has gone. It answers the awe of Okunoin and gives the whole Koyasan sequence its one summit.