I do not know what the highest the PS2 ever sold in a year in Japan, but the DS was able to push out over 8.3 million at one point in the past.
The 3DS has two Pokemon games coming, Luigis Mansion, DQ game, Monster Hunter, etc. It is already selling like hot cakes. People are buying whatever games they can get their hands on no matter how small. PSP sales will probably cut in half or more this year. I think the 3DS will push out over 10 million units in Japan this by the date I post in the title.
But I promise there will be huge numbers over there this year, multiple times. I know I am forgetting at least one big game, and there is bound to be many more this year alone.
You think it will not even get close or it has a shot? This year the 3DS could even beat the DS's highest year ever!