PS3s really are not selling well at all in Japan. Here are quotes about the situation from several people who live there:
As bad as PS3s are selling in the US, they are selling even worse in Japan. To this point, only 500k PS3s have been sold in Japan (those are the official numbers). If Sony really did ship 1M to Japan, than 500k PS3s are languishing in Japanese stores, unbought.
Wiis sell out instantly in Japan..they can't be kept in stock. Nintendo has already won the next gen war in Japan (and probably did in Europe and the US as well). I think Wii will be a landslide victor in Japan, just as the DS is.