Underneath it is a selection of attractively priced safes.

The display is not exactly a buzz with custom.

Negative interest rates, NIRP, has certainly thrown things off-kilter.

But for now, at least there's no mathematically compelling reason

for ordinary Japanese to spend 25,000 yen on a metal box to keep their cash at home.

The 0.001 percent rate, Japanese banks offered a normal deposit account remains minutely above zero.

And the Bank of Japan's policy has been crafted to ring fence individuals.

The big unanswered question, most pertinently for the yen, was it reels around in search of a natural post-NIRP range against the US dollar.

It's what those Japanese individuals are actually doing with their cash.

The enigma has deepened following the ministry of Finance's most recent weekly portfolio data.

For the week ending on February 19th, a week that saw the NIRP coming into force

and spectacular Japanese net buying on foreign bonds and foreign stocks.

The former was the largest readings since the date it became available in 2005.

And the latter represented a 500 percent increase, over the previous week.

What will market can only nervously guess at?

Until March 8th; however, is the breakdown of that buying.

The crucial answer to how much of the action was banks' pension funds

and the sort of investment products that Japanese individuals tend to favor.

The bank's purchases would tend to be currency hedged.

While the pension funds and investment trusts would not.

If the breakdown shows out the bias were banks', the yen may belly twitch from its 112 to 113 range against the dollar.

But if it emerges that the outflows came from trusts, boiled with money that s* refuses to sit in the safe,

the market may but heavily on weeks more of large, yen depressing unhedged outflows.