At a recent sales and product explanation meeting for retailers, Nintendo revealed that in its first four days of availability since May 25, New Super Mario Bros. sold through 900,000 copies in Japan. This makes it by far the best debuting DS game ever, and one of the highest debut for a game in Japan in the last few years, topped only by recent hits such as Final Fantasy XII, Dragon Quest VIII and Pokemon FireRed/LeafGreen.
Nintendo also mentioned that 950,000 DS Lite systems were sold in April (not including the older model, which also sold well). That brings total DS sales to 8.4 Million in Japan alone. Another notable success was Tetris DS, which shipped through 800,000 units in 4 weeks.