[2009] What actually causes ayu's sales to drop?

[SunshineSlayer]

There are so many reasons for this. Way more than the 3 listed.

The most basic answer is that generally speaking, people in Japan just don't really care much about her anymore and/or her personality gets on their nerves.

I don't think there is really any question that it is the hardcore fans that are primarily driving her sales these days. But this topic has been done to death basically.