Yes personally I wouldn't use pine shavings, even kiln-dried, but I doubt the pine shavings are kiln dried anyway, as outside Europe they tend not to be.
Looks like you can get Carefresh on Amazon in Japan
I don't know how expensive that is though.
Amazon.co.jp: Carefresh:
This 14L bag looks good
Amazon | CareFRESH?NaturalTM Premium Soft Bedding 14L Bag, 2.2 Lbs. by Carefresh [
or this 60 litre bag works out more economical but more to pay up front
Amazon | carefresh Complete Pet Bedding, 60 L, Natural by CareFresh [
Also this hamster blog has some links to pet shops in Tokyo, if that helps.
Hamster Stuff in Japan - Dwarf Hamster Blog