Quote from sibrag:
That is the result of unwinding of the "carry trade" - due to near zero interest rates in Japan, in the 'good old days" big players borrowed in Japan, sold yen bought USD or EUR then played in international/commods markets. Now the opposite is happening. Unwinding their positions, thus going to cash - be it EUR USD - then buying JPY. So to complete the circle .... selling stocks (markets down) buying yen (strong yen). On the yen side, you also have locals, selling their international holdings, and also going back to yen.
fwiw