Nikkei ''3DS first shipment was 400k, it sold out''
Source:
Nikkei.com
Nikkei is the leading financial, business and industry news outlet in Japan.
For comparisson here are previous Handheld Launch Sales Figures for Japan.
QUOTE1998.10.21 (Nintendo GameBoyColor) - 155.774 (5 days)
1998.10.28 (SNK NeoGeoPocket) - 21.471 (5 days)
1999.03.04 (Bandai WonderSwan) - 102.655 (4 days)
1999.03.19 (SNK NeoGeoPocketColor) - 18.809 (3 days)
2000.12.09 (Bandai WonderSwanColor) - 145.975 (2 days)
2001.03.21 (Nintendo GameBoyAdvance) - 611.504 (5 days)
2002.07.12 (Bandai SwanCrystal) - 30.692 (3 days)
2003.02.14 (Nintendo GameBoyAdvance SP) - 117.859 (3 days)
2004.12.02 (Nintendo DS) - 441.485 (4 days)
2004.12.12 (Sony PSP-1000) - 166.074 (1 day)
2005.09.13 (Nintendo GameBoyMicro) - 148.117 (6 days)
2006.03.02 (Nintendo DS Lite) - 67.653 (4 days)
2007.09.20 (Sony PSP-2000) - 263.538 (4 days)
2008.10.16 (Sony PSP-3000) - 155.720 (4 days)
2008.11.01 (Nintendo DSi) - 170.779 (2 days)
2009.11.01 (Sony PSP Go) - 28.275 (1 day)
2009.11.21 (Nintendo DSi LL) - 103.524 (2 days)
SOURCE: Famitsu via
NEOGAF