Japan is not a physically large country, so the SAL system for mail, Surface Air Lifted, would not account for a mail delay of more than two days before being loaded onto a plane for Australia. I should think directly to Melbourne, but if another Australian city, you could perhaps add a couple of days for more sorting and a short flight.
More sorting in Melbourne, at worst surely two more days, in total perhaps just over a week and that would be quite reasonable.
Clearly I wouldn't be mentioning this if the delivery of a Christmas present from our Friend in Japan was timely. Take a guess when it was delivered to us after it was postmarked 30th November 2019 in Japan?
If you live in Melbourne or have driven in Melbourne and you already know, please let others have a guess. If you live interstate, I am impressed that you know, but again please others have a guess.
It is an illuminated road sign. What is it about? Check back in twenty four hours after this is published for answers.