Trust banks such as Sumitomo Mitsui Trust Bank Ltd, traditionally the main providers of inheritance services, are facing a push from banks such as Mizuho, which are seeking to bolster their asset management businesses as negative interest rates sap returns and demand for loans remains tepid.

Providers of inheritance trusts are licensed by Japan's financial regulator and consumers have on the whole escaped the widespread misselling of financial products that saw Western financial institutions fined billions of dollars by regulators.

Due to a rock-bottom birth rate, Japan's population is shrinking and aging fast. The government predicts the population will fall to barely 80 million by 2050 from 127 million last year. By then 40 percent of people will be over 65, compared to 27 percent last year. They're also expiring faster than ever: the national death rate spiked to 10.4 deaths per 1,000 people last year from 9.5 in 2010.

But they are wealthy. Over 60-year-olds own more than half of the country's $14 trillion in personal financial assets, according to the Bank of Japan.

The Japanese government, however, wants a bigger slice.

Japan already has among the highest inheritance tax in the world with a top rate of 55 percent, and changes introduced last year lowered the threshold for paying the tax to $280,000 from $471,000.

In the United States, the threshold is $5.5 million with a top rate of 40 percent, while numerous countries including China and 15 OECD nations have no inheritance tax.

Keeping It In The Family

At a recent seminar in Yokosuka, a port city southwest of Tokyo, retirees sipped green tea and listened as a speaker laid out options for inheritance, applauding as the talk ended.

"I ought to think of how I can move money a little at a time to my wife's name, or within my family," said Hideo Tsujii, a spry 83-year-old. "I want them to estimate how much I have in assets, then I can decide what to do."