Just what does it take to keep Japan's companies happy?

They asked for a cheap yen to help boost overseas sales -- and they got it.

The latest trade data shows Japan's exports rising at their fastest pace in three years.

Even shipments to China posted healthy growth, despite lingering tensions over a territorial dispute that flared up last year.

But a Reuters survey shows sentiment among manufacturers slipped in September from a 3-year high the previous month.

The main concern? Weakness in emerging markets, where some firms see demand undershooting forecasts.

At home as well, Prime Minister Shinzo Abe's largely successful growth push has come at a price.

While exports are climbing, the weak yen has pushed up import bills, with Japan posting its longest streak of trade deficits in 30 years.

The country's growing reliance on imported fuel after the Fukushima nuclear crisis is a big reason for that.

With Japan's reactor recently going offline, and winter on the way, the situation is unlikely to improve anytime soon.

Electricity costs are rising, and could become a major headache for energy-intensive industries.

Abe also has yet to detail how he will offset the impact on companies of a planned sales tax hike that some say already has consumers tightening their belts.

So though Abe's scored a few points for the country's corporates - not to mention a successful Olympic bid - some of his victories are starting to look like a double edged sword. Positive data may reassure the markets - but companies are likely to stay nervous.