The March earthquake and soaring yen rocked Japanese companies.
Now, the US and European debt crises and the prospect of a global economic slowdown could weigh on the nation's exports, threatening the country's recovery.
The currency's rise to levels close to post-Second World War highs prompted Japan to sell yen last Thursday in the first market intervention since March. That day, the Bank of Japan added ¥10 trillion of monetary stimulus.
Masaaki Kirakata, the Bank of Japan governor, yesterday said volatile exchange rates could have a "negative effect" on the country's economy. The yen traded as high as 76.83 per dollar yesterday, up from the post-war high of 76.25 per dollar.
In addition to the severe drops in global markets fuelled by Standard & Poor's downgrading of US government debt late on Friday, the Organisation for Economic Co-operation and Development's composite of leading indicators for June, released on Monday, showed possible slowdowns in the economies of the major importers: China, the US and western Europe.
If that materialises, sales of everything from cars and gadgets to household equipment will suffer.
The West's problems are already putting pressure on the yen, while competitors from South Korea and other Asian countries are being helped by their currencies weakening versus the yen.
Still, forgotten in all this is the strength many Japanese companies have shown, from dealing with the yen to getting production back up quickly after the quake.
Another haven currency, the Swiss franc, has shown a huge overvaluation, forcing the Swiss central bank to step up its fight to counter the franc's surge to a record.
The Swiss National Bank yesterday said it would "significantly increase" the supply of liquidity to the money market and expand banks' sight deposits to 120 billion francs from 80bn francs. It will also conduct foreign-exchange swap transactions to create liquidity, it told Bloomberg News. The "Swissie" weakened after the decision, trading at a record 1.0373 versus the euro this week. It was at 1.0075 in trading yesterday, bringing its gains to 20 per cent this year.
Nestle, the world's largest food company, based in Switzerland, said yesterday the franc's strength removed 14 per cent of its profits for the first half of the year.