Analysts at Scotiabank explained that the JPY is the second best performing G10 currency over the past 5 days.
"Japan’s fundamentals are not as rosy as those in Switzerland. Its current account surplus has recovered some ground in the past couple of years having shrunk to just 0.8% of GDP in 2014. That said, last year Japan ran an ugly budget deficit of -5.7% of GDP and, irrespective of the fact that the BoJ’s enormous QE programme is shifting debt from private to public hands, the size of the overall debt burden is startlingly large."
"That said, liquidity levels in the JPY are extremely good. Its position in Asia often means that it captures a lot of safe haven flow from that region and during that time zone. Also, the fact that as a G7 nation the Japanese authorities are pressured not to intervene in the market may also bias some investors towards the JPY and away from the CHF during times of stress. In contrast to the Japanese authorities, the SNB maintains FX intervention as a currency tool. The main purpose of this is to push back against speculative inflows with have kept the CHF at overvalued levels for many years. Like other developed nations, all the currencies mentioned so far benefit from a strong, stable and transparent systems of governance and legislation. The latter can also be said about the USD."