That's really a pointless claim. Sony & Nintendo are Japan based, most of our games still come from Japan. Their sales numbers are absolutely insane for a country of their size, especially the opening sales you mentioned.
It's just a different habit: The Japanese audience tends to abandon "old" stuff and jump on new stuff much quicker than the rest of the world. Look at the GBA, GC, even PS2. Same for the software: Incredible sales for 1-3 weeks, then a steep drop.
If you were refering to the situation right now: I think Japan's enthusiasm for the Wii has cooled down quite a bit, but the PS3 (let alone the 360) can't capitalize on that fact yet. So the Japanese are waiting for the next move each company is going to make - will Nintendo refuel the Wii craze with Mario Galaxy, Wii Fit & their 2008 lineup? Or will Sony win them over?
Currently playing: NSMB (Wii)
