This is a pretty cool discovery that I've made recently, these appear to be some kind of collector/trading cards for handheld games. Obviously from Japan, this is a picture of the front and back of 3 different cards. Each card is about 2 inches by 1 1/2 inches, and they are fairly thick cardboard. I have a complete case of these, and a few extra packs (I'll be adding pics of the case soon, and maybe more of the cards, I have about 12 of them loose now...)