The BoJ is still buying lots of JGBs (blue). As long as that's going on, it makes no sense for the MoF to intervene to strengthen then Yen (black). Such intervention quite simply can't work. If Japan wants a stronger Yen, BoJ needs to stop buying JGBs...

The Yen is falling because Japan's yields are artificially low. Whenever markets think fiscal risk rises, like now with a possible election, the Yen falls. Intervention won't fix this. Instead, the gov't needs to sell assets and retire some of its debt...