In the case of the US, you can improve this further:
Find a friend who lives near a Mitsuwa, JAS Mart, or similar Japanese grocery (there are several here in NYC).
Have him buy the candy there in bulk (enough to fill all the US-bound orders anyway), and use the relatively cheap USPS flat-rate shipping to send it to US subscribers.
i.e., avoid buying in Japan (which is more expensive b/c of VAT) and avoid shipping from Japan; the chain groceries have done the hard work for you, so you can reap the benefits.
You can find the low-hanging of the Japanese pop snacks (Pocky, Yan-yan, Koala's March) at any Asian market in a top 100 major US city; but you won't find, for example, limited edition Soda flavored Kit Kats or Meiji Wintertime Fuwafuwa chocolate or anything crazy cool like that.
That's where a service like this would shine, I reckon.
There are a lot of seasonal candies that are not available out of Japan. I don't live in the US anymore but when I did I never saw any of the more original candies in the Japanese groceries...
For example, at one time, they had wine kitkats in Japan.
Find a friend who lives near a Mitsuwa, JAS Mart, or similar Japanese grocery (there are several here in NYC).
Have him buy the candy there in bulk (enough to fill all the US-bound orders anyway), and use the relatively cheap USPS flat-rate shipping to send it to US subscribers.
i.e., avoid buying in Japan (which is more expensive b/c of VAT) and avoid shipping from Japan; the chain groceries have done the hard work for you, so you can reap the benefits.