After months of defying forecasts, the yen ended last week with a near vertical plunge under its belt and the glint of more craziness to come. The Japanese authorities have opened their playbook to the page on fake intervention. A glut of central bank announcements next week looks sure to revive the turmoil.

It may be a difficult time to be a forex analyst, but it looks like a brilliant moment to be a Japanese robot.

The yen’s sharp plunge against the dollar this year has highlighted some pressing questions around Asia’s largest developed economy. Japan is a resource-poor country that imports most of its energy, food and raw materials; it has let wages stagnate for two decades and must now protect a shrinking and ageing population that has largely forgotten the pain of inflation; its corporations have moved almost 40 per cent of their manufacturing capacity overseas since 1995, blurring the picture of whether a weak yen is fundamentally good or bad for industry.