A trait that is present in not a few but all of them is how polite and courteous they are. Not only amongst themselves, but they extend the same courtesy to foreigners too.
A trait that the Japanese are known for - picking up after themselves. The value and importance of cleanliness has been taught to them since early childhood. The schools have no assigned ‘cleaners’ since they are taught and expected to clean up after themselves. They shocked the world during the FIFA World Cup, when (even after they lost) the Japanese remembered to clean their side of the stadium and not leave a mess behind.