It's remarkable that Japanese export volumes continue to fall despite the collapse of the yen. Standard economic theory would not predict that.
As @gelgoog said, industrial structure can't be changed immediately. It takes years to do that.
The effect probably would not be immediate.
If I was the government of Japan I would just let the Yen totally collapse. It would probably solve all their financial problems.
It would make their enormous debt, mostly in Yen, trivial to pay for example.
Collapse of Yen would be extremely catastrophic for its citizens:
- Massive Inflation: food, energy, other raw materials.
- With collapse of Yen, the people's labor in nominal terms gets devalued.
- Massive capital flight leading to a drag on the economy
- Even investments might not come in if the currency keeps depreciating, until the depreciation has stabilized.
- Massive human flight, already I have been seeing reports in Japanese media of foreigners trying to switch to Korea or other countries. With major depreciation, there will be a flight of both domestic and foreign talent.
It does not matter if Japan has a positive balance of trade. The question is can they get positive balance of trade or not.
If your goal is simply to get a positive trade balance then maybe yes (even this is not necessary). The negative effects though are incredible as listed above.