Sleeping Bags (winter) UPDATED

[Andy OCJ]

For Japan I recommend getting the cheaper local brands.

UPDATED OCT 2020
I can no longer recommend UK RAB down sleeping bags. Quality seems to have dropped (recent purchace problems) and I found out the company had been taken over several years ago.

This is for cold areas and snow mountains (-15C or lower) you will need a better sleeping bag. Okutama etc you can use a cheaper one.

In Japan (winter sleeping bags- snow mountain areas)
You can get a winter sleeping bag on sale or online for about 30- 35,000+en if lucky. Most are older models but ok.
Basically you need 750-800g of down inside (羽毛量) sleeping bag to be warm. Fill power (FP) is also a consideration but most big brands use the same quality. Full weight should not be more than 1.4kg for good one. It can also be used in spring and autumn for high or cold places.

Recommended!
PuroMonte sleeping bags are a bit cheaper (32,000en old model for 800g down 羽毛量 ).
Fill power of the down is not best quality but ok for -15C.

Recommended!
Nanga (Japanese brand).
Quality is good (35,000- 42,000en depending on model and shop) . Waterproof breathable material outside. Ok....
Montbell Downhugger #0  ok if you find on sale or old model that is cheaper.DO NOT get 1,000 gram down filled bags (-20C). Too hot and can only be used in January and February. Also big and heavy.

I do not personally recommend synthetic fill sleeping bags - heavy and very large pack size. They are cheaper though and not a problem if a bit wet.