The Azusa River is a river within the Hida Mountains or Northern Japanese Alps, in the western region of Nagano Prefecture, Japan. The river belongs to the Shinano River watershed, and forms the upper section of the Sai River. The name of the river comes from the catalpa tree found in the river basin, which are used for Azusa Yumi, a sacred bow in Shinto rituals. The river gives its name to the Azusa limited express train, which is operated by the East Japan Railway Company, and which runs mainly between Shinjuku Station in Tokyo and Matsumoto Station in Nagano.

Kamikōchi is a remote mountainous highland valley within the Hida Mountains range, in the western region of Nagano Prefecture, Japan.