Thanks.
For my next Question, Will American Points cards work on a Japanese Wii Shop Channel.
As mauifrog said you need to delete your current account (you will lose all your current channels) and then change the region. Then you need to use a Japanese Wii Points card to add the points and buy whatever you want.
tl;dr
It's not worth it unless you want a permanent Japanese console.
Don't you lose ALL re-download rights for EVERY American game that particular Wii console has EVER purchased?