The Chichibu-Tama-Kai National Park spreads over 1250 square kilometers in the mountainous and woody region at the junction of Tokyo-to, Saitama, Nagano and Yamanashi prefectures.
The park has 20 peaks of over 2000m, an estimated 2,800 plant species and a variety of mammals, such as deer, squirrels and monkeys, all in their natural habitat.
Famous peaks include Mt Kobushigatake (甲武信ヶ岳, 2475m) marking the intersection of Saitama, Nagano and Yamanashi prefectures; Mt Kumotori (雲取山, 2017m) at the junction of Tokyo-to, Saitama and Yamanashi prefectures; and Mt Daibosatsurei (大菩薩嶺山, 2057m) in Yamanashi prefecture.
The extend of the National Park means that it is accessible from several locations. There are three common approaches : Chichibu, Oku-tama or Enzan stations.
One of the most scenic area is Nishzawa Gorge and the splendid Nanatsugama 5-tiered waterfall (七ツ釜五段の滝) in Yamanashi prefecture. To go there, take the JR Chuo Line from Shinjuku to Enzan Station (90 minutes and ¥3,190, by Limited Express), then a bus (¥1,200) from the station to Nishizawa Keikoku (西沢渓谷).
Chichibu
Chichibu is accessible via the Seibu Ikebukuro Limited Express Red Arrow line (75min, ¥750 from Ikebukuro). You can get off at Seibu Chichibu station, near the famous Chichibu-jinja Shrine or at Yokose station, if you are intending to climb start climbing immediately.
If you want to save energy, the Chichibu Railway will bring you to Urayama-guchi (6min from Seibu Chichibu, ¥230) to access the Hashidate Stalactite Cavern, or Mitsumine-guchi (21min from Seibu Chichibu, ¥430), which drops you near a cable car to reach the 2000 year-old Mitsumine-jinja Shrine (the building is of course more recent).
Oku-tama
The trail from there continues to Oku-Tama, via Mt Kirimogamine, Mt Kumotori and Mt Takanosu. You can start from Oku-Tama station and do the trek the other way round as well.
Mitake-san & Otake-san
Another popular hike is Mt Mitake-san, accessible from Mitake station, four stops before Oku-Tama on the Ome line. Take the bus (5min, ¥270) in front of the station to Mitake-san Cable Car station. The cable car (¥1,050 return) will transport you from 400m to 800m. From there it is a leisurely 15-min walk through the upper reaches of Mitake village to the 1200 year-old Mitake-jinja Shrine. From there, paths through the woody mountains lead to Mount Hinode and the craggy Mount Ohtake (1266m), as well as the Ohtake Cave and Yosawa Cave.