There may be other ways, but I’d do it like this:

1. download Anki for PC and login with your account (make one if you haven’t)
2. import the decks and sync with AnkiWeb by closing Anki oder clicking on the sync button in the top right corner
3. login with your account in AnkiDroid and tap the sync button

Just make sure you use the same Version of Anki for PC and Android.
Personally I have Version 2 on both. AnkiDroid 2 is still in beta, but I haven’t run into any problems so far.
I find the cards and decks easier to manage and create on PC than on my phone, so I use this for most things and I just use my phone to review.

• This reply was modified 11 years, 11 months ago by  Tobias.

I agree. I love how Koichi has designed those lessons. Keeps me motivated unlike many other japanese learning sites.