If you want to see the collection of Japaneseweapons

In U.S. there are some military museums to display them.
Mostly in East Coast.
There are at Springfield, West Point, Aberdeen,Quantic,Fort Benning, Smithsonian and Oregon.
At Aberdeen, Army Ordnance Museuma has a largest collection of them including three tanks.

In Japan there are not many and their collections are not complete.
The biggest one is at "Yushuukan Museum " of Yasukuni Shrine in Tokyo.
I saw many visiters from overseas visiting there. It locates at the center of the city.

There is one more in the Weapon's School of Self Defence Army at Tsuchiura. But this is not open to public. It took one hour half driving to there from the city.

For the Japanese , weapons are still taboo and teachers, parents tell kids that they are bad objects.

There are some open sky markets all over the country.
The best customers for the military good are collectors from overseas who collect wartime items.
They are mostly younger people and very keen to search their items such as gears , photos, optical weapons, maps and so on.

see, http://japaneseweapons.com
http://blogs.yahoo.co.jp/japaneseweapons