National Art Center exhibition tickets?

I see there is a big exhibition of art by Magritte opening at the National Art Center, Tokyo, in March. (http://www.nact.jp/english/exhibitions/2015/magritte2015/index.html)

We will be in Tokyo for the opening days. It says advance tickets are on sale. Does anyone who has been to this sort of exhibition know whether we will need to have advance tickets, or can we just show up on the day?

(In some Western countries an exhibition like this would sell out well in advance.)

If we need tickets, can these be purchased somewhere, from abroad?
Thanks

advance tickets are sold out except ticket C which include an official photo book(3800 Yen).
You can purchase the ticket at the entrance with 1600 Yen for adult, 1200 Yen for University/college students and 800 Yen for High School pupils.

Normally, there are things and admission limit to matrix to enter the museum, there is not much that ticket is sold out.
However, because this day there is a lecture of Royal Museums of Fine Arts of Belgium of director, it may be very crowded.
Advance tickets privilege is attached seems to have sold out.
If you are worried about, ticket for the smartphone seems to buy also in English.
https://tixee.tv/event/detail/eventId/7918