There are two of the Garber kites in the collection, the other is the FW-190 (both look in very good condition). The museum has 400 kites on display in a very tiny space, with about another 3500 in storage. It`s located in Nihonbashi, Tokyo. Some of the kites date back quite a few years. I have posted more information on the museum on my blog Around Tokyo.
Here in Japan militaria is widely traded. The only restriction is with swords, there is a huge market here for then, but even if they are rusty and useless they must be registered with the police.