Tokyo stock prices are at fifteen-year highs, but Japanese corporations remain pessimistic about the country's growth potential as Abenomics has fallen short of expectations, analysts say.

"The demographics are negative - Japan is a super-aging society, not a growth market," Fujitsu (Tokyo Stock Exchange: 6702.T-JP) Research Institute senior economist Martin Schulz told CNBC by phone on Friday. "Japanese corporations have adapted and their strategy is to look for growth overseas."

More than two years after Prime Minister Shinzo Abe returned to power, a sharply weaker yen has boosted profits at blue chip exporters, spurring a sharp stock rally. But a recent government survey confirmed that Japan Inc remains pessimistic about the outlook for economic growth.

More companies plan to hold back from new capital investments, this year's survey showed; the proportion planning new investments over the next three years was down 1.9 percentage points on-year, at 64.5 percent.

"Companies still do not believe in Abenomics," said Mizuho Research Institute chief economist Hajime Takata in a note published on Friday. "After fifteen years of deflation, corporate Japan's mindset remains conservative," he added by email.

Expectations and reality

Still, while the broader economy is struggling to recover from the three percentage point consumption tax increase in April 2014 that tipped the economy into a technical recession, many of Japan's blue chip corporations are thriving on a weaker yen.

Toyota Motor (Tokyo Stock Exchange: 7203.T-JP), for example, is set to post a record profit for the second year in a row. The company's stock has soared 77.9 percent over the past two years.

But most of the gains in profitability over the past couple of years that have propelled Japanese stocks to fifteen-year highs came from cutting costs, rather than investments, analysts said.

"Corporations are still stuck in the same retrenchment mode that has prevailed since the [post-war economic] bubble burst [in the early 1990s]," said Mizuho Research Institute's Takata.

Indeed, Japan Inc's economic outlook remains conservative: In fiscal 2015, companies only expect the economy to grow at roughly the same pace as it did the last two years -around 1.3 percent - according to the Cabinet Office's survey of 2,445 listed companies released on March 3.

The government is more optimistic though, forecasting gross domestic product growth of 1.5 percent.

Different Japans

Just like Tokyo is booming while the countryside falls by the wayside, Japanese companies are adapting to the absence of growth in their home economy by looking overseas or carving new businesses catering to an ageing population.