Have you heard of the 'subscribe and save' service from Amazon Japan? As far as I know it's new. It seems to only be available for food and drinks. But it looks quite good, if you have a regular item you have delivered it might be worth looking into.
I don't really have many things that I cannot buy locally or from my grocery delivery service (Co-Op) but we cannot live without Weetabix. I buy two cases every few months from FBC in Kobe.
If I were to set up a subscription from Amazon it would be for these: Baked Beans. I could live on them. In fact I was craving them last night, a night when both Noodle and Mr. Mee a Bee were not in for dinner. Little Guy and I wanted something easy.