When I bought my imported graphite black ds from Lik-Sang last week, I also bought a 220V adapter along with the ds.
The japanese DS comes with a 110V adapter, but it only works in Japan (and USA?)
And the 220V adapter works fine, I have tested it.
Also I have to some advertising here, Lik-Sang is having a free shipping worldwide for all their DS consoles. You only need to buy one game with the console and you get to choose any of the four shipping options which normally cost like up to $40.