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The Nikkei ended 1.5 percent higher at 18,765.47, the highest level since December 2015.
Risk appetite got a boost after China reported upbeat trade figures with exports and imports both beating forecasts.
Tokyo Electric Power Company Holdings Inc jumped 18 percent after a source said Japan will increase an interest-free loan by more than a third to 14 trillion yen ($123 billion).
The broader Topix gained 1.5 percent to 1,512.69, while the JPX-Nikkei Index 400 also added 1.5 percent to 13,545.11.