i'm pretty sure that Disk Union won't ship outside Japan, so unless you have someone in Japan who's prepared to ship it on to you, that would be difficult. Amazon Japan
will ship abroad, though their shipping charges can be ruinously expensive for a single CD. The ordering process is exactly the same as it is for any other Amazon, and you can turn on ordering in English. Which means the only problem is finding a Japanese release if you don't read/write the language.
Is this the release you mean?
http://tinyurl.com/m85tpyYou could also try CD Japan.
If all this sounds like a headache, some of the bidding/shopping proxy services previously discussed here should be able to sort you out.