The explanation many analysts have found is that yen and gold are considered safe havens. However yen has not proven to be good at keeping value over the years. Other analysts think the reason JPY and gold move together is because both depend on real interest rates in USA. And that might be true if no other factors are involved. When the oil prices shake, gold moves, but not necessarily the yen. Same thing happens when a big collapse or a war is foreseen beyond the horizon.
If the above is true, that doesn't mean that we can take practical advantage of this correlation, unless we happen to understand the driving forces of gold besides interest rates.
