@viago , if you have Japan version of your Wii U, YES you can play with other Games Region you need to Mod your Wii U and use a software/app called Spiik into your Wii U console.
With Spiik, will not work just few Nintendo first party game (but are really few of them) and to work also with them you need to change the language Game once you will install into your Wii U Console...
@0xabad1dea, @Kenpham , the news that you gave I belive it's quite big for this comunity because no one till yesterday knows that could be possible to CHANGE the Wii U language with just replace the system files.....Because everyone says that can srew up your Wii U console as the console it's Region Locked.
@0xabad1dea Please, I suggest you to open a new topic in this section with this BIG NEWS man, and write the procedure and some picture or video proof of it!!!!!!