They'll have one more to add to that number later this year if Sony keep on being totes sick like this.
Whoa whoa whoa wait wait wait. Should I buy a Japanese PS4 from Japan when I go to Japan this year?
That'd depend when you'd go to Japan this year. If it's at the same time as launch, you can forget about it. Pre-orders have been snapped up a long time ago and everytime Amazon JP came up with a new one, it's gone in minutes just like in other countries. You can try lining up in front of Yodobashi or Bic Camera when PS4 launched in case they have some extra units. But lining up outside in Japan's winter is not my idea of fun.
Unless you go to Japan in Autumn, or 6 months post launch basically, you have much better chance at getting one by pre-ordering in your own home country.