I've come across this Japanese cover. I'm guessing the date is Showa 14 which makes it 1939. The postmark isn't clear enough to make out the town. Can anyone tell this cover's origin and destination? I've included the letter if there's any hints in there. Also what is the purpose of the purple box handstamp on front? I'm guessing the little red oval handstamp is a mark from the sender, but correct me if I'm wrong please.