Worldwide PlayStation Vita sales were 1.8 million at the end of March 2012, Sony has revealed.

Those numbers - withheld from Sony's annual earnings report - tumbled from a follow-up earnings call this morning.

"About Vita," said Sony CEO Kaz Hirai (via translator), "the last year, [we sold] 1.8 million units for US, Japan, Asia and Europe. And as a starting phase, I think it was a good start."

Sony announced 1.2 million worldwide Vita sales at the end of February 2012, which means that 600,000 Vitas were sold during March.

"Oh don't worry about me - just getting into gear, plod plod."

Extrapolated, that's 1.8 million Vita sales a quarter, which isn't bad - the 3DS managed 2 million from January to March this year.

Sony expects there to be 16 million combined PSP and Vita sales this financial year (April 2012 - March 2013). The Ace Consulting analyst questioning Kaz Hirai reasoned that PSP would contribute roughly 6 million sales towards this - a generous estimate given the PSP's annual decline.

Therefore, the remaining 10 million sales - to reach the projected 16 million target - will have to be made up by PlayStation Vita.

Kaz Hirai appeared to agree, stating that "the volume is as you imagined".

Can Vita manage it? At a pace of 600,000 sales a month, as in March 2012, the answer is no - that would give 7.2 million sales. What, therefore, has Sony got up its sleeve to significantly boost that monthly tally?

Of that 600,000 figure, an overwhelming majority must have been made up by the US and Europe. Why? In March (including two days of February and a day of April), Vita only managed 52,492 sales in Japan.

"A game platform, like Vita - the software is the key to success, how good the software is. We have to reinforce the software area in order to improve the business, that is the basic line." Kaz Hirai, CEO, Sony Corporation

Assuming the US sold the lion's share, given the size of its market, why didn't Sony mention the presumably decent-if-not-impressive numbers during its reaction to the March NPD sales figures?

Hirai went on to stress the importance software will have in Vita's future success.

"A game platform, like Vita - the software is the key to success, how good the software is," he said. "We have to reinforce the software area in order to improve the business, that is the basic line.

"And vis a vis Vita, at this moment, there is no decline or lack of motivation as a portable platform. And also, in order to connect with the Network, this is a very important product indeed for us, and therefore we still have a very high motivation to develop this further. There is no change. And services and software must be strengthened.

"In other words, the collaborative approach is very important, so is third-party. And from first party studios, the titles will be presented one after the other, so please look at them and give your evaluation based on them."

PlayStation Vita launched in December in Japan, and in February in Europe and the US.