PlayStation Vita sold 321,407 units in its first two days on sale in Japan.
The Enterbrain-collected data, revealed by Japanese magazine Famitsu (via Andriasang) covers sales for Saturday 17th December and Sunday 18th December.
Famitsu notes Vita's opening two day sales failed to beat the Nintendo 3DS' opening two-day sales.
3DS sold 371,326 units over the two-day period 26th February and 27th February in Japan.
The PlayStation Portable sold 166,074 units on launch day in Japan: 12th December 2004.
Last week Japanese media reported that Sony shipped 700,000 Vita units to cover the launch period. Sony has only said it shipped 500,000 units of the 3G/Wi-fi model as a limited edition that includes 100 hours of free 3G access, and expects to sell through this stock quickly.
More sales information is expected later this week when Media Create releases its figures for software and hardware.
Meanwhile, a number of Japanese Vita owners have reported technical issues with their new consoles. Some have even found it freezes, locking them out of the system.
Sony Japan issued a notice to its customers, admitting it had received "many inquiries" to its Vita Information Center. It updated its website with a Q&A for issues frequently encountered by customers, including power cuts, freezing in mid-operation, failure to connect to data service and inability to register a PSN account.
Vita launches in Europe on 22nd February 2012.