Looks like Japanese are trading in this game in large numbers, judging by amazon.co.jp only offering 454 yen ($4.50) trade-in value for it today:
I have never seen such a low trade-in value for a game upon release. For reference, most games that are in demand are offered for trade-in value up to or even over their MSRP in the first week of release, unless there are mass trade-ins. Even today, popular Nintendo 3DS games command trade-in values upwards of 2000 yen, months or even years after their release.
Could this be a sign that the used market will be flooded this week, which might in turn affect sales of new copies?