My father had a piece of hand written piano score entitled 'The Japanese Anthem' - it consisted mainly of a set of chords and their related arpeggios. I never got an explanation as to where it originated, but I sensed it was a WWII 'parody piece' - it was much in the same class of music as 'chopsticks' or 'down at pappa joes' - dead easy for 'non-musos' to play on the piano.

My dad was in the RAF in WWII - and served in England/Scotland up to V.E. day, then came back to Australia till V.P. day - meeting with USAF pilots there.