My first custom is their appreciation for beauty. People during the Heian period prized elegance,fashion,and beauty. Both men and women groomed them selves with great care. If the were to meet anyone out of japan they could give a good impression to japan's women and clothing.Women had 12 different silk robes to show lovely colors of fashion.
The second custom was cultural influences.Prince Shotoku came to power in 593 and cultural influences from Asian's mainland had been reaching for hundreds of years.The gov. of japan took an active interest in Korea and Chinese culture.This helped structure in society because theses cultural influences would not have been brought to japan if Prince Shotoku didn't come to power because when he did the culture reached all the way to get to Japan. Confusionism and Buddism would have not been introduced.
My third choice of custom was social ranking.The amount of folds depends on where your placed on the pyramid ranking.The ranks were Shogun,Daimyo,Samurai,and Peasants.If Japanese people didn't have ranking this could affect way people treat each other.Also get to use whatever fan and mess up part of culture.