Nature in Japan

Hello,
I'm going to Tokyo at the end of september for 2 weeks and would like to spend a couple of days somewhere foresty, quiet, with not too many tourists. I would love a cabin/cottage but I guess it get's expensive.. Does anybody has a suggestion??
Thank you in advance!!

Plenty of areas. For example https://abnb.me/QxXYMoGk5Y

Last trip we went to Chichibu and stayed at Hotel Miyama in a room with a private onsen bath (which I mention because it was very reasonably priced but a huge room really nicely decked out). Chichibu is a rural area with a string of towns linked together by a little railway. While the towns are mainly along the river and there are some fields and things there, there are forests and mountains about including a temple at the top of a mountain with spectacular views (I'm told, I didnt go there but I am going to go back and will go there when I do).

The area is not popular with overseas tourists and foreigners are a bit of a novelty, though it is popular amongst Japanese. I really enjoyed it. Nagatoro looked to be the most lively town but I would go back to Hotel Miyama which was spectacular inside, especially after seeing its unassuming exterior.

If you would like to spend somewhere foresty, I think that Hakone Kyukaido where you can enjoy hiking trails very quietly would be one of the best options for you.
Hakone is very famous for its history,nature and onsen, but I personally think that
Hakone Kyukaido is not so much known yet among tourists.

There are a lot of tourists around famous place in Hakone, but once you have gotten to the Hakone Kyukaido, you can�ft probably see them , but nature.

https://www.japan-experience.com/city-hakone/the-best-hikes-in-hakone

The closest station to hike is Hakone Yumoto, It takes about less than 2 hours by train from Tokyo!
I am not sure if there are good accommodations with reasonable price around Hakone Kyukaido, because I have never stayed there. but I checked some and found out that there were some guest house.
https://motohakone.com/�� This guest house seems Japanese style.

Have a nice trip to Japan!