Because of history and geography, all Japanese who are alive today are the result of an accidental selective breeding program which emphasized order, cooperation, self-sacrifice, conformity, and following the leadership.
To whatever extent the Japanese constitute a race, their sense of order which precluded looting is an inbred racial characteristic just as the tallness which has resulted in a mostly-black NBA is a racial characteristic.
Various answers were posited:
The Japanese are a highly civilized people — which would have been news to the 22 British watchkeepers on the island of Tarawa who were tied to trees, beheaded, set alight, and tossed in a pit less than 70 years ago.
Alternatively, Japan enjoys the benefits of being an ethnically homogeneous society — which didn’t prevent the ethnically homogeneous West Country of Britain from being wracked by widespread thievery during the floods of 2007.
Most analysts overlooked the most obvious factor: Looting is a young man’s game, and the Japanese are too old. They’re the oldest society on earth.