TOKYO (REUTERS) - In the shadows of Prime Minister Shinzo Abe's formidable PR machine, a small, tenacious group of "Abenomics" detractors is battling to be heard and waiting for their "I told you so" moment.

Being a contrarian in a society that values consensus and conformity is hard enough, but it is even harder for academics, commentators and investors who are attacking Mr Abe's economic revival plan as misguided and potentially dangerous.

The plan relies so much on changing attitudes formed during years of decline that critical voices are more than just part of the political debate.

Criticism could undermine Mr Abe's efforts and there are many sceptics reluctant to openly challenge policies that are giving Japan long-forgotten optimism and hope.

Business and consumer sentiment surveys are pointing up, stocks are on a six-month bull run, the yen is in retreat, boosting exporters' profits and Mr Abe's support ratings exceed 70 per cent. But that is what gets some detractors worried.

"Since ancient Greece and Rome, most policies that excited people ended in failure," says Mr Kaoru Yosano, who served as finance minister in past Japanese administrations. He was in the cabinet in 2007 when Mr Abe had his first stint as prime minister.

"The fact that people are pleased and in a festive mood seems to prove this policy won't work," the veteran policymaker told Reuters in a recent interview.

So far, Mr Abe's remedy for two decades of economic under achievement - a mixture of fiscal pump-priming, "shock and awe" monetary stimulus and a promise of pro-growth reforms - has an impressive, and growing, list of endorsements.

Most come with a caveat that tackling Japan's deep-rooted structural problems and a credible plan to contain the nation's runaway public debt are paramount.

Yet the message from global institutions, including the International Monetary Fund, prominent economists, market gurus and business leaders is that "Abenomics" is a welcome experiment, even "Japan's last chance."

Unlike sceptics who reserve their judgement until Mr Abe's growth strategy due in June, the detractors dismiss it as a mere distraction: old ideas, such as state backing for "growth industries" and some minor deregulation, sold under a new brand.

So instead, they focus on what is in plain view: the Bank of Japan's assault on deflation backed by a 2 per cent inflation target that its new chief, Mr Haruhiko Kuroda, vows to reach in two years with a massive burst of stimulus amounting to US$1.4 trillion (S$1.74 trillion).

The detractors question the focus on "creating inflation", the 2 per cent goal and talk of a lack of a credible path to get there.

They fear that blind faith in the central bank's firepower replaced a cool-headed assessment of economic reality and doubt a monetary shock can shift Japan into higher gear.

They add the BOJ's buying spree of government bonds could backfire dramatically if Mr Abe fails to come up with a credible budget reform plan and investors lose faith in Tokyo's ability to manage its finances - it already has the heaviest public debt burden among leading economies - without central bank help.

A resulting spike in bond yields and a yen selloff would wreak havoc in Japan's financial sector, they say.

Critics, such as Mr Seki Obata, Keio University business school professor who in January published a book Reflation is Dangerous, argue that "Abenomics" is exposing Japan to such risk without any clear sense of what it can accomplish.

That is also the concern of Mr Ryutaro Kono, Paribas BNP chief Japan economist, who was nominated last year to join the BOJ board only to be rejected by lawmakers as too cautious.

INFLATION, JOBS AND REALITY

Detractors question the plan's central premise that ending a downward creep in prices will help spur economic growth and that the benefits now felt by stock market investors and exporters will spread to broader economy.

"The 2 per cent inflation is an inappropriate target. I can't see how a rate of inflation can be the goal of an economic policy," says Mr Yukio Noguchi, an economics professor who this month published a book titled Japan Will Collapse Under Monetary Easing.

They cite Britain as a case in point. It is skirting with recession, yet has inflation of close to 3 per cent.

Mr Noguchi says the BOJ has not explained how pumping more money into an economy that has the world's biggest stash of household and corporate savings is meant to spur investment and lead to higher prices and wages.

In general, Abenomics dissenters side with Mr Kuroda's predecessor Masaaki Shirakawa, who saw deflation more as a symptom than a cause of Japan's headaches.

"If there was a single thing that would have cleared the fog and solved all problems, Japan wouldn't have been in this situation for 15 years," he said on March 19, his last day in office.

As expected of former governors, the No. 1 enemy of the "reflationist" camp has since kept a low profile, but a group of like-minded critics keeps chipping away at a strategy they say badly needs a reality check.

For example, Mr Obata says there is no way incomes can rise across the entire economy because the baby boomers in fast-ageing Japan are now retiring to be replaced by young workers with entry-level wages.

Japan's overall consumer spending power will therefore fall, rather than rise as Abe hopes.

"Individual companies may offer wage increases, but because of demographics it is simply impossible to increase the total amount that is paid out in wages," says Mr Obata. "On the contrary, that amount will shrink."

Critics also warn a weakened yen is much more of a mixed blessing today, when Japan is running trade deficits instead of big surpluses.

It may help exporters, but others feel the pain of more expensive imports as illustrated last week when Japanese squid fishermen stopped work for a couple of days in protest at high fuel costs.

Right now Mr Abe looks unstoppable. Helped by a steady flow of well-timed policy announcements he is on course to consolidate power won in the December lower house landslide with a win in an upper house election in July.

One reason is that no one is proposing a clear alternative, a point made by Mr Yuuki Sakurai, who runs the US$16 billion Fukoku Capital Management and is critical of Abenomics, comparing BOJ actions to "shooting a sparrow with a cannon".

The bottom line, detractors say, is that there are no simple solutions or shortcuts.

"For the Japanese economy to truly improve, we will need to make the same kind of efforts as in the past," former finance minister Yosano says. "That is work hard, create new technologies and try to sell goods abroad."