Collectors’ cards and little action figures seem to be very popular here; they often come along with a chocolate bar or some pieces of candy. My lab group had a whole box of candy bars, and were selling them for 50 yen apiece (about 50 cents). So I enjoyed a waffley, chocolatey thing, and when I was done I had a neat Gundam card.
Some are holographic. Mine is partially transparent. It’s sitting on top of one of the technical documents I’m reading at the moment.
Here’s a little action-figure-slash-bottlecap that came along with a lemon twist Pepsi I bought a few days ago.

