According to Japanese site 4Gamer.net Sony has seen sales fall from 321,400 units sold in the first two days to 72,479 during the past five days.
Plagued by operating systems bugs and "poor quality" claims the device at $325 is also seen as expensive when compared to the highly popular Nintendo 3DS.
Observers said that reasons for the relatively poor sales aren't clearly known, but may have something to do with the relatively poor quality and limited games.
Cost may have been a separate problem. The Vita is much more expensive than both the PSP and the 3DS and still needs a separate storage card to be usable.
In Japan the device has fallen to fifth popular gaming device.