Pythagoras calls three the perfect number, expressive of ?beginning, middle, and end,? and he therefore makes it the symbol of the divine. The Japanese, too, are fond of this number, and the Japanese-language Wikipedia has an enormous page with lists of "the best three... (fill in what you like) in Japan," ranging from nature, architecture, religion, food, history, to life and entertainment.

Here is a selection:

[Mt Fuji - photo Ad Blankestijn]
The Three Sacred Mountains (San Reizan)
Mt Fuji (3,776m), the perfect conical volcano at the border of Shizuoka and Yamanashi Prefectures that is the symbol of the whole country. In the course of history, there have been 18 eruptions, the last one in 1707. Since ancient times, Mt Fuji has been regarded as a sacred mountain by the Japanese. Tateyama, a group of peaks in eastern Toyama Pref., with snowy ravines and beautiful alpine flora (the main peak is Mt Oyama at 2,992m) forms the NW outpost of the Northern Japanese Alps. Mt Hakusan (2,702m) is a famous volcano on the border of Ishikawa and Gifu Prefectures, and like the other mountains above two, a pilgrimage center. The Shinto shrine Shirayamahime near Kaga-Ichinomiya Station stands at the foot of the mountain and affords a good view of its peak in clear weather.[Kegon Falls - photo Ad Blankestijn] The Three Great Sacred Waterfalls (San Dai-kotaki)
The Nachi Falls (133m) in southern Wakayama Pref., in the Yoshino-Kumano National park - contrary to what you w...