Goldman Sachs said the yen was now overvalued by 20pc, or two "standard deviations" out of kilter. It was even more over-valued against the dollar in the mid-1990s but that is scarcely relevant. Over 60pc of Japan's rebound in exports has been driven by Asia, and only 13pc by the US. What matters is the yen rate against China's yuan. That has reached a crucifying ¥12.4. The vice grips ever deeper.