3 months after the PS4's release in North America and Europe, the console has launched in Japan last saturday. According to Famitsu, the PS4 sold 322,083 units during its launch weekend.
The PS4 launch sales surpass that of PS3, which sold 88,443 units in its first two days, but Sony's next-gen console still falls short compared to the PS2, which sold 630,552 units in the same time period. Siliconera also points out that the PS4 sales in Japan are very similar to the Wii U during its launch weekend, which sold 308,570 units.
Considering that the PS4 has sold 5.3 million units as of February 8, we can assume that the console is nearly, if not at, the 6 million mark.