According to Japanese data firm Media Create's weekly game and console sales figures, the PlayStation Vita sold over 324,000 units in the first days following launch — but it's looking like sales dropped off sharply soon afterwards. If Media Create numbers posted on NeoGAF and 4Gamer.net are accurate, PS Vita sales declined to only 74,479 in the week ending on December 25th, while every other console on the market saw an increase during the same timeframe. We're still waiting for Media Create to officially post these numbers to its site, but NeoGAF posters Road and Chris1964 have consistently shared accurate Media Create data for months, and the post is backed up by other sources as well.
Since launch, it appears only 80 percent of the 500,000 PS Vitas that reportedly made up the first shipment were sold, which could point to a weaker launch than expected. Of course, it depends on where those systems were shipped: the 500,000 might also include handhelds sent to other territories. Still, while Sony went on record saying that Japanese pre-orders had sold out, spot checks at several Japanese e-retailers show the Vita still in stock. That said, a console's lifespan is often a marathon instead of a sprint — with only a few weeks of sales data available, we'll hold off on writing the Vita's obituary.
Update: Media Create has posted the weekly numbers, which match exactly with what we've seen elsewhere.