great western paintings

are paintings Western purchased by the mega rich Japanese available to be seen by the public Monet, Gaugin, etc, if so where can I see them

The national museum of western art in Ueno has a collection of 16 Monet works, half of which is on display now, and several Gauguin works in addition to a large collection of other western paintings.

For more info:
http://www.nmwa.go.jp/en/

At sompo japan museum of art in sompo japan building in Shinjuku, you can see the well-known "Sun Flower" by van Gogh.

http://www.sompo-japan.co.jp/museum/exevit/index.html

If you are greatly interested in impressionism, you may also like to visit bridgestone museum in Kyobashi.

http://www.bridgestone-museum.gr.jp/en/