The average life expectancy of a Japanese man is the highest in the world at 79.1 years: a magnificent tribute to a diet of rice, tofu, pickles and fish. But from the private equity point of view, it’s a nightmare.

There’s a good reason that Japanese companies don’t discuss concepts such as “corporate DNA”. Western companies may need to enshrine the founder’s original dream as some complex genetic inheritance; in Japan, the founder is still sitting upstairs in the corporate suite, giving the orders.

And the Methuselah-esque lifespans of Japanese has created a buyout bottleneck that reduces even the most swashbuckling of corporate raiders to tears of frustration.

The geriatric chief executives don’t want the foreigner’s money, they don’t want change, they don’t want to globalise and, most critically, they don’t want to step down. A buyout, even one that would clearly invigorate management and offers to propel the company into the stratosphere, will happen over their dead body.

But nobody — even the sprightliest of septuagenarian Japanese chief execs — is totally immune from Old Father Time. Old age, long-overdue retirements and a slowly dawning sense of crisis may be about to transform Japan into perhaps the greatest buyout opportunity on earth. Just a little more patience is all that’s required.

On paper, corporate Japan — in its listed and unlisted forms — should be a buyout merchant’s feast. Even in these dark days of liquidity shortage, the big buyout merchants reckon they could lay their hands on the necessary cash if Japan’s doors could be kicked ajar. There is extraordinary depth of quality, lots of quirky products where Japan is unique, and plenty of situations where the only thing holding these companies back from world domination is timid, unimaginative management. And, say the value investors, it’s all for sale at bargain prices.

Friday’s intemperate sell-off of Tokyo shares delivered another cruel laceration to many stocks that deserve better. It is fine to think of markets as the perfect arbiters of value, but the truth is that only a tiny proportion of the Japanese stock market is analysed at all and, by some estimates, nearly 45 per cent of stocks are trading at below their company’s book value.

The astonishing range of Japanese industry, from industrial robots and specialist chemicals to animation studios and achingly trendy shoemakers, presents the private equity buyer with a child-in-sweetshop situation. Dozens of Japanese companies hold greater than 50 per cent global market shares in a particular product: often the invisible components without which not a single iPod or mobile phone would exist. And then there are the mighty conglomerates — the Hitachis and Toshibas of the world whose hundreds of subsidiaries are ripe for acquisition and turnarounds.

But the longevity frustration is not just about a few old men’s resistance to change or acquisition. It is a failure of imagination. These are chief executives who just, at some point about 15 years ago, became too tired to cherish a vision. The private equity case for charging into Japan is not just that there is mouth-watering value to be had, but that the turnaround story is so astoundingly simple. Japanese companies need to globalise and need managements that passionately want to stamp their mark on the world. Once the bottleneck shifts, runs the current theory, the next generation of management may be happy to watch the company flourish via foreign capital.

Nobody wishes the corporate codgers any ill, of course. But within the next 18 months, the generation that built Japanese industry from the ashes of the Second World War will be hitting that magical age of 79.1. Given what is out there in terms of value and industrial strength, it is a fairly short wait for what could be the greatest private equity bonanza of all time.

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