It's definitely not a typical good luck flag for carrying into battle etc. There are no names on it. Somebody put a date (1943) on the far left side which is odd. And almost the whole thing is written in hiragana which is very odd indeed. I can only read bits and pieces like "your life for the sake of the country" and "strength." But given how haphazardly it's written including the main element (大日本ばんざい) I would guess maybe it came from the postwar cottage industry where they created these "fakes" to sell. But it does look quite old and might look interesting on a wall. Anyway hold off until you get other opinions.