Our experience started with some frustration as we could not purchase the catalog ''Van Gogh and Japan'' at the end of our visit (friday 9PM).
We could see piles of thoses books and no more customers were allowed to enter the shop.
But, as your webshop is well organized, we managed to order the books we wanted.
And somebody from the boutique answered twice the proper answers.
So we just ordered 2 more books 5 mn ago...
Improvements or suggestions
Maybe inform visitors at what time the shop admittance is closed.
My japanese wife and myself were so impressed by the Museum and by the"V.G. and Japan"exhibition that we could have spent more time watching...