because after sterling kena pounded, they yearn for yen.
ok seriously, yen is on an upward trajectory compared to other prominent currencies for some time this year and they know the boj and finance ministry will not do abe's bidding anymore by further easing and will instead strengthen the yen to tame inflationary pressures in japan. abe will not be top dog for long and they're back to being uptight arses again in currency tightening.