Tokyo is a huge city, and by and large a flat one; not a place usually associated with mountains and hiking. But at its western periphery, this enormous metropolis runs into the wall of the Okutama mountains (which technically are part of Tokyo), so the hiking in Tokyo is better than you might expect. Although you can’t usually see these mountains from places like Ikebukuro and Shinjuku, if you go up to the viewing decks of Tokyo Tower, the Skytree, or the various skyscrapers which have them, you’ll see the mountains in the distance (on a clear day, anyway). You might even see the looming bulk of Fuji behind them, but don’t count on it; that mountain is famously elusive.
So, while Tokyo isn’t quite a hiker’s dream like Kyoto or Seoul (where you can see the mountains right there in the city), it’s surprisingly easy to get from the neon and concrete to the mountains and forest, and there are plenty of good options for day hiking in Tokyo just an hour or two from Shinjuku.
The most famous Tokyo hiking trail (and easiest to access) is Mt Takao, just an hour from Shinjuku station and offering cultural interest (temples and tengu) along with the scenery. It’s a very popular spot for Tokyoites though, so perhaps not the best choice if you’re wanting to escape the crowds.
Heading a bit deeper into the mountains, there is the Okutama area. There are many, many hiking options here; the two I’ve covered are the pleasant Okutama Mukashimichi (Okutama Old Road) hike to Lake Okutama, and Mt Kumotori, Tokyo’s highest peak. The latter is over 2,000m and involves some fairly tough terrain, usually done as a 2-day affair. If you want to have a crack at doing it in one day, my report should be of use.
If you’re in Tokyo and want to stand on top of a mountain but don’t fancy something as involved as Kumotori or as busy as Takao, neighbouring Yamanashi prefecture (beyond Okutama) has lots of mountains and few people. Mt Kuratake is a nice Yamanashi day hike you can do from Tokyo, and you’re likely to have the mountain to yourself.
For something less strenuous, the hiking trails of Kamakura (south of Tokyo) can be enjoyed in combination with visiting the temples and the Great Buddha.
And of course, you could always tackle the big one – Fujisan.