"deep & rich green tea cube chocolate". Manufactured by Meiji. Purchased from 3shel1d on eBay.
The packaging shows the chocolates covered in a cocoa powder, but they were individually wrapped, so I guess the powder was pressed into the chocolate. They are still pretty good, like cubic bonbons or truffles. They're about the width of a thumbnail, so one can easily eat a whole box of I lost count how many. It was easy.