The Chichibu-Tama-Kai National Park spreads over 1250 square kilometers in the mountainous and woody region at the junction of Tōkyō-to, Saitama, Nagano and Yamanashi prefectures.
The park has 20 peaks of over 2000 metres, 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, 2,475m) marking the intersection of Saitama, Nagano and Yamanashi prefectures; Mt Kumotori (雲取山, 2,017m) at the junction of Tōkyō-to, Saitama and Yamanashi prefectures; Mt Kinpu-san (金峰山, 2,599m) and Mt Daibosatsurei-san (大菩薩嶺山, 2,057m), both 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 Nishizawa-keikoku Gorge (西沢渓谷) and the splendid Nanatsugama-go-dan-no-taki (七ツ釜五段の滝 ; "Seven toads five-storeyed waterfall") 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.
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 Mitsumine-jinja Shrine (三峯神社), which traces its origins 2000 years ago.
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.
Mounts Mitake-san & Ōtake-san 御岳山 & 大岳山
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 Ōtake (1266m), as well as the Ōtake Cave and Yosawa Cave.