Originally Posted by giorgioCh
-"We do not ship to your country"
-"You need a Japanese account + Japanese credit card in order to use the reader"
"Even if you manage to bring it to your country I'm afraid we cannot assure you of a regular compatibility"
That is not correct, or at least incomplete.
All the current Kobo devices support Japanese no matter where you buy it. You can change the interface to use Japanese. They support a Japanese dictionary and English to Japanese translation dictionary. There have been complaints about the Japanese dictionary, but some of them were fixed in the latest firmware and someone has built an alternative dictionary to install.
I think the second point is more related to buying books from the Kobo/Rakuten shop. This has been discussed in the Kobo forums, but I don't remember the details. But, if you have a source for Japanese ePubs, you can sideload them and read them.
I think that if you can get your hands on a Kobo ereader, you will be able to use it to read Japanese books wherever you are. If you want more details, have a look in the Kobo forum.