Mount Koya, or Kôyasan in Japanese, is one of the most important centers of Japanese Buddhism. Located on a 3000 foot plateau high in the mountains of central Wakayama prefecture, the great monastic complex at Koyasan is the headquarters of the Shingon sect of Japanese Buddhism, which boasts 10 million adherants and controls over 3000 subsidiary temples across Japan. The Buddhist tradition at Mount Koya began in 816, when the great monk Kukai founded a monastery there to compete with his rival Saicho's Enryakuji monastery on Mount Hiei. Throughout Japanese History Enryakuji and Koyasan were the two great centers of the esoteric Japanese Buddhist traditions, and constantly dueled with each other for control of the shifting tides of patronage and prestige. Nowadays, Koyasan seems to have won. While Enryakuji never fully recovered from being torched by Oda Nobunaga in 1571, Koyasan is more famous than ever, drawing millions of visitors from around the world every year with its scenic mountain beauty, its towering cedars, and its role as the starting point of the Pilgrimage to the 88 temples of Shikoku.
A visit to Koyasan can be a bit overwhelming at first arrival. Although the mountain doesn't have anytwhere close to the 1,500 temples it boasted in its 16th century heyday, it still retains more than 110 seperate temples. The most important temples to see are the Kongôbuji - the main Shingon monastery where the head abbot resides, and the Garan complex of temples, which includes the Kondô (main hall) and the iconic Daitô (Great Pagoda). Also worth a visit is the Reihôkan Museum, which displays the great artistic treasures collected in Koyasan's 12 centuries of patronage by emperors and shoguns.
But the main highlight of any trip to Koyasan is walking through the vast Okuonin cemetary, set solemnly among towering cedars, a who's who of Japanese history if there ever was one. In the 11th century it became fashonable for wealthy lords to entomb hair or ashes of their families near the tomb of Kukai so that they would be close at hand at the time of the great saint's fortold reawakening (according to legend, Kukai never died - he just went into a "long meditation"). This practice continues today, and any Japanese Buddhist worth his salt has part of his remains, or at least a lock of hair, entombed on Koyasan to insure a prime position when Kukai and the Buddha of the Future return to save the world. In the Okuonin, you can visit the tombs of all the great names in Japanese history, including such lights as Uesugi Kenshin, Takeda Shingen, Senhime, Date Masamune, and the Tokugawas. Even villains such as Akechi Mitsuhide and Ishida Mitsunari get their places of respect.
You should definiately stay overnight at Koyasan. There are no hotels on the mountain - instead you stay in a real Buddhist temple, known as a shukubô, sleeping on tatami and and partaking of the tradtional temple fair known as shôjin ryôri, a remarkably healthy vegetarian meal prepared according to strict rules without any meat, fish, onions, or garlic. During your stay, you will also have the opportunity to participate in daily rituals of a Japanese temple. Staying in a shukubô is a truly unique experience, and not to be missed if at all possible. Prices start at ¥9000, and include two meals.
Lastly, Koyasan is the site of two festivals you should keep in mind if visiting Japan in the summer. The Aoba Matsuri, on June 14 and 15, celebrates Kukai's birthday as a horde of monks appear and conduct a variety of special rituals. Most interesting, however, is the Rôsoku Matsuri on August 13, when thousands of candles are placed in the Okuonin cemetary in remembrance of the departed.