Does anyone know how to get Japanese music on a UK/US version of i-tunes. To download the J-version of i-tunes means you have to delete the UK/US version - and loose that selection of dowloadable songs. The two stores are no reconciliable - anyone know how to get around this?
Try installing the US version of iTunes on your iPod (or some other separate drive/partition) and then launch that one when you want to do some shopping.
EDIT: Hmmm, rereading your post, I may have missed your point. All the songs get moved over to the same iTunes Music Folder, regardless of the version of iTunes (J or E).
If you have j-mp3's, try double clicking them (to copy and play in iTunes) if they are not being seen by the US iTunes. That, or dragging them into your iTunes library.
Normally, to switch which region (country-wise) in iTunes you just click on "Choose Store" arrow, which is above the "Choose Genre" in the left column.
I didn't see a Japanese store, just the usual US and the new European stores, but then I only have the US version of iTunes.