Kamikochi is a popular resort in the Japanese Alps, offering some of Japan's most spectacular mountain scenery. It is open from mid/late April until 15 November, and shuts down during winter

Kamikochi is a roughly 15 kilometre long plateau in the Azusa River Valley, about 1500 meters above sea level. Part of the Chubu Sangaku National Park, Kamikochi has only been moderately developed with half a dozen hotels, a few shops, mountain huts and hiking trails. To preserve the pristine wilderness of the area, private cars are banned from Kamikochi, and access is only possible by bus or taxi. 
In the centre of Kamikochi stands Kappa Bridge, from here hiking trails lead up and down the valley and towards the summits of the surrounding mountains. The area offers a huge range of trails, from trails with mostly flat terrain, requiring no hiking experience and only a few hours of time to climbs to the surrounding peaks that are more challenging and only recommended between mid June and mid September for experience hikers. 
Kamikochi is particularly beautiful during the autumn foliage season, which usually peaks in mid October. A wide range of alpine flora can be viewed from May through October, with the best time being mid May through July. Among the wildlife to be observed are monkeys and various birds. 

Access: 2hrs 40mins from Shinjuku (Tokyo) to Matsumoto Station by JR Chuo Line (limited express), and 30mins from Matsumoto to Shin-Shimashima by Matsumoto Dentetsu Line. 1hr from Shin-Shimashima Station to Kamikochi by bus.

Further information: 
Kamikochi Official Guide
Matsumoto City Guide to Kamikochi