Famitsu reporting earlier that 476,000 copies had been sold in the first few days of release. According to Media Create, that figure sneaks in an extra 11,000, as they're only tracking 465,000 in sales for the first week (via Gamasutra).
Despite the missing units, the launch provides some interesting statistics. MGS4 moved over 12 times as many units as its closest competitor, Mario Kart Wii (38,000), and more than double that of the non-Metal Gear top 10 combined. Sorry, Snake, there's no place to hide in Japan.