My great uncle was in the Coast Guards during WWII and from one of his tours of duty he brought back a box (about the size of a necktie box, full of these, and I will state what is on them...The Japanese Government One Centavo in the upper left and lower right corners it says PK the denomination is "1". There is something in in tiny Japanase writing in the middle bottom of the bill. These are Very small (smaller than Monopoly money) bills and I thought they were funny money he got while in service as some kind of joke.I remember my father telling me that his Uncle gave them to him when he was a kid. I have a few of these bills that are pristine condition but have no one to aske about what they are and WHY would Japan have the word "centavo" on their money which seems to infer something to do with Mexico or Spain?? I am not very WWII saavy so pardon my ignorance please. Thank you for any help on this odd WWII question.