I live in the US. I upload all my songs from my laptop using Itunes match. I then move to Japan and take my laptop with me. Will I be able to stream my songs over the cloud (not download, just stream)?
I doubt it. iTunes Match is based on copies in the iTunes Store, and each country's iTunes Store is restricted to use in its own country.
Make some other arrangements to hear your music in Japan.
That will be no problem. I am currently doing the exact same thing. Streaming songs from my German iTunes Match subscription in Japan.
Apple doesn't restrict access to the stores based on your actual location.
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