^ The second floor shop now only sells Idol goods (at least when I was there). So the first floor shop now IS the old second floor shop.

That one more and more is specializing in idol group tickets though. The Shibuya and Ueno ticket shops are the best bet for Ayu tickets these days. And as Polka just mentioned there are tons for this tour and extremely cheap too, so you won't have a problem. Probably wouldn't even have a problem buying them the very day of the show for completely bottom of the basement prices (like 2,000 yen)