Kanto Region (関東地方)
The Kanto region is, without a doubt, the most popular place for non-Japanese to go hiking in this country. With its vast network of public transport links, you can pretty much go anywhere in Japan from Tokyo: all it takes is the money to get there. Some hardcore climbers even hit the peaks of Nagano prefecture as a day trip by jumping on the first Shinkansen.
Map of Kanto Region (関東地方)