The game was heavily bundled, there was the wallmart deal and black friday. The US is also almost 3 times as big in Japan, yet the console boost for the week was roghly half week over week, not even taking into consideration the basic pricedifference... so no, I highly doubt that MW2, as a monster that is was even close such a big console mover in the US for the 360, as FFXIII was for the PS3 in Japan At least thats my opinion...
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