Reports out of Japan put the Vita's launch figures well ahead of the PSP's debut, but significantly below that of the rival 3DS.
Famitsu reports Enterbrain has recorded 321,407 Vita consoles sold in its first two days on sale in Japan, December 17 and 18.
Based on current sales data, Enterbrain estimates the console's first week sales will reach 1.4 million.
For comparison, the Japanese launch of the 3DS saw 371,326 units sold in the first two days, a good 50,000 more, before sales stymied ahead of the August price cut.
The PSP, which went on to become one of the country's best-selling consoles, moved around 166,074 units on its first day; figures for its second day are not available.