This is the entrance to the Ghibli Museum in Mitaka.
The false entrance, that is. The real one’s over here:
Sadly, not only can’t you buy a ticket from Totoro, you can’t get one at the real entrance, either. Domestically, they’re only available at Lawsons convenience stores, and they sell out weeks or even months in advance. There’s a block reserved for foreign tourists, fortunately, but you have to order them through specific travel agencies.