The economy has shrunk almost 10 percent in the half decade since Shinzo Abe was last prime minister, as a soaring yen hollows out manufacturing. Abe's return may be exporters' best chance yet to halt the damage.

Abe's calls for unlimited central bank liquidity have taken the yen down about 5 percent against the dollar since mid-November, as his Liberal Democratic Party led pre-election polls, then romped to victory Sunday. Futures traders boosted bets on yen declines to the most since July 2007, when the currency traded around 120, compared with about 84 Friday.

The wagers reflect a groundswell of concern among policymakers, including Abe and departing economy minister Seiji Maehara that the Bank of Japan hasn't enacted sufficient monetary stimulus to end deflation and revive the economy. Critical to the yen's outlook will be whether Abe can secure BOJ action to set and achieve an inflation target, according to Jim O'Neill.