Good news for iOS users!
The long-awaited Japanese course has been released in Beta on iOS! Unfortunately, us Android users have to wait a little longer, but congrats to the Japanese team!
FYI, it's not released on the computer yet, just the mobile iOS.
I believe my account is synced with the Japanese course (as I am going through the Japanese course on my iPhone), that's probably why I can access it on my browser.
However, I should add, there are no notes in any of the lessons at the moment, so it is purely guess work =]
Another issue is I have no Japanese keyboard at the moment, so I am having to use a different website which is pretty frustrating.