^ I wouldn't throw out the competition, merely because it's "limited". Not all limited releases are truly that limited...
But yes. For Ayu to get number one in this week, she definitely CAN'T drop any significant amount more (I'd say no more than 20k, definitely, but that shouldn't happen, I don't think..), and Arashi needs to not sell more than average (which also shouldn't happen, but you never know) - selling much more than 50k will probably screw her over. I mean, since the last single was two weeks combined, you figure the first week was probably between 60k and 70k, right? And this single shouldn't drop in sales too much, but you know it should drop at least somewhat. Plan on right under 70k, tops (if she exceeds that, then YAY!), though probably between 50 and 60......
It'll be very close. I honestly think she can do this, though. The sales you guys listed for Arashi's second weeks really bumps up my confidence. If we look at those, and also at what this single is, it should sell around 40k, and if that's the case, I'm not worried at all. It all comes down to if a freak occurrence comes up, lol. (Like, if Arashi magically sells 60k the second week, or if Ayu's sales plummet to less than 50k the first week or something...) But I do have a good feeling about these next three singles. Rock'n'Roll Circus is doing great, and now fans are very hyped about this project. I have faith that she can do this.