Maybe the easiest solution is 100yen gas bottle burner - Iwatani is main brand. Good for short trips. I know people have used in winter even.
Gas is often less than 100en for a few days cooking and you can buy anywhere - convini, department store, gasoline stand.
Use a 100en pot for cooking.
Also very good is a free stove - make your own aluminum alcohol can stove - see below!
Gas Stove (Iwatani)
In Japan you can buy a burner for about 2,800 - 3,500en which will use cheap 100en gas bottles. Many members use and ok for most trips.
I think Iwatani gas stove - Tokyu Hands sell them. Internet is cheaper.
Can buy that gas anywhere.
イワタニ カセット ガス ストーブ (100円 bombe) New Model see link!
Iwatani cassette gas Junior Compact Burner CB-JCB
I often use an expensive burner (Optimus multi-fuel) that can use anything... gasoline, kerosene (best/easy to buy/cheap), even cooking oil and Vodka ok.
They are expensive... not recommended for first time buyers.
Kerosene is very easy to get in Japan and you can fill up a 1L bottle for 50yen at a gas stand. Lodges in the Alps at 3,000m
will give you some or sell if needed.
Alternative! Make your own!
You can use 100en shop pot and free beer/soda can stove - make yourself.
All you need to buy is 250en alcohol from chemist/pharmacy 'nenryou alcohol'.
Youtube and google
https://www.google.co.jp/search?q=beer+soda+can+stove
