Nirro ("Sunny Splendor"), the name of a range of mountains in the province of Shi-motsuke, on the main island of Japan, about 100 m. N. of Tokio, famous for its scenery, and for being the burial place of the greatest personage in Japanese history, Tokugawa Iyeyasu, the warrior, lawgiver, and founder of the last and greatest dynasty of shoguns, which held the military power of Japan from 1003 to 1867. The highest mountain of the range is Nan-Taizan. The sanctity of Nikko dates from A. D. 767, and from the most ancient times it was the seat of one of the many Shinto deities whom the early Buddhists transferred to their pantheon, under the general title of Gongen. It contains a vast number of temples, shrines, pagodas, monuments, and religious edifices of all kinds, and has long been the favorite resort of thousands of pilgrims. The village of Ha-chiishi lies at the entrance to the holy places. At the decease of Iyeyasu two nobles were commissioned to select a suitable burying place for his body. In 1617 the shrine and many of the surrounding edifices were completed, the corpse deposited, the Buddhist high mass celebrated, and the title of Dai Gongen conferred, whence lyeyasu is often called Gongen Sama. Iyemitsu, grandson of lyeyasu, and the third prince of the line, is also buried at Nikko. From an early date the chief priest of Nikko was a prince of the imperial blood.

The gifts of vassal daimios and of pious pilgrims have so beautified and sanctified the place as to make it, both as to nature and art, the most attractive in all Japan. Seven miles from the tombs are the lake of Chiuzenji, and the famous waterfall of Kiri-furi (falling mist), which is more than 700 ft. high.