TOKYO—Toru Noda, the chief executive officer of Wal-Mart Japan Holdings, was on a flight back to Narita airport from Orlando, Fla.—fresh from Wal-Mart's annual manager's meeting—when the captain made an announcement 30 minutes before landing: There had been a massive earthquake and their flight was being rerouted to Hokkaido, the country's northernmost island.

The 50-year-old Mr. Noda was terrified. His wife and two children were in Tokyo when the quake hit. "It was only later that I realized it was up north," he said, dark...