The 3DS has not started off as well as thought it would in Japan, being well below the GBA and DS launches, although with the DS launching during the holidays it is not a completly fair comparison. Still the 3DS is above the PSPs launch, which also launched during the holidays, and we all see how succesful the PSP is now.
For now I think it is just that Nintendo did not have the right mix of games in Japan for launch, or a big release since then. If Resident Evil and Zelda are not enough to boost the 3DS up some in June, then I'll start to be concerned that the 3DS' problem is more than just a lack of compelling software for the region.
My initial guess was that 3DS would sell 4 million by the end of 2011 in Japan, which would put in on par with the DS' first full year. I think it should still be able to do that, and I would consider that a successful start.
