Sony, Toshiba, and Nintendo are in trouble. The Japanese tech stars pin half their troubles on the Yen, which reaches parity with the greenback in The Economist's latest Big Mac Index. The other half: we’re not buying as much of their stuff.

It’s a moot point whether the Yen has become over-valued. The Economist’s latest Big Mac Index (which uses the cost of the iconic American burger to measure purchasing power parity) came out this week, and finds the Japanese still a shade undervalued against the US dollar.

Still, the Yen is now far stronger than it was 12 months ago, and three of Japan’s tech icons partially blamed the currency for their woes as they announce results and forecasts today.

Nintendo: game over
Nintendo continues to win the game console war with Microsoft and Sony. The company’s Wii console has now sold 45 million units – including 10 million in the past two months alone, driven by the new Wii Fit balance board accessory, easily outpacing Microsoft’s Xbox and Sony’s PlayStation3.

Despite shifting more consoles, Nintendo says its profit slumped 18% in the first nine months of its financial year. With 90% of sales outside of Japan, Super Mario’s maker has been hit hard by the rising Yen. The company also said it expects Wii’s rampant growth to slow during 2009.

Sony: losses ahead
Sony confirmed previous guidance that its profit fell 95% to $US115.2 million for its October to December quarter as currency woes combined with less demand for the company’s flatscreen TVs, game consoles, camera and products across the board. Revenue fell 25%. Sony added a grim coda today, saying it expects to make a loss for its current quarter, and the full year.

As previously announced, Sony will lay off 6000 staff. A rep for Sony New Zealand told NBR the company was still waiting to hear from Tokyo whether it would be affected.

Toshiba: worst result since 1949
Toshiba reports it will swing from profitability to record its biggest loss since 1949 for its current fiscal year. For the 12 months to March, the company expects to be $US3.1 billion in the red.

Revenue fell 21% during the company’s December quarter on weaker demand for the company’s products, with its memory chip, LCD panel, consumer electronics and home appliance divisions all suffering.

Toshiba says 4000 employees will be made “temporarily” redundant.