Where's all the butter gone?

Who doesn't like a bit of butter on their pancakes? I had some very tasty pancakes today for lunch, only slightly marred by having to smear margarine over them instead of butter because we had run out. In fact, we haven't been able to buy any butter for three weeks now (despite visiting every supermarket and convenience store in cycling distance). Neither has one of my students. There is something of a butter crisis going on. My student became aware of it when she noticed a handwritten sign in a Tokyo convenience store proclaiming "We have butter!" She ran in only to discover they had run out. Apparently, Japan had a major surplus of butter and milk a couple of years ago, so the dairy herds were given their marching orders. Now, with imported butter suddenly unavailable (anything to do with dwindling oil supplies?) there's none of the off-white gold to put on the shelves, proving you can't have your cake and eat it, not for a long while yet.