Momiji River runs down through a valley on Mt. Omoshiro, which lies to the northeast of the city of Yamagata.

A hiking course along the valley enables you to enjoy nature throughout the four seasons, and it is very popular with sightseers.

The valley is especially beautiful between late October and mid November when the leaves turn red or yellow; this change is called 'momiji' and is the origin of the name Momiji River.

The 2km hiking course takes about 40 minutes to walk along slowly. Here and there running into the valley are waterfalls such as 'Wisteria Waterfall' and 'Illusional Dragon Waterfall'. Moreover, there are many unique rocks in the valley such as 'Whale Rock' or 'Treasure Rock'. And there are many strange ones, too.

Visitors can enjoy a variety of views of the river; some parts of the river are broad and some run between rocks. The canyon is also very popular among photographers.