May 5th is Children's Day, also called boy's festival. It is a day to respect children's personalities and to celebrate the healthy growth and happiness of children. It became an official national holiday in 1948, but it has been a day of celebration in Japan since ancient times.

On Children's Day, families with boys raise huge carp-shaped flags outside the house. They display dolls of famous warriors and other heroes inside. The carp was chosen because it symbolizes strength and success. Rice cakes wrapped in oak leaves and filled with sweet bean paste, called kashiwamochi, are traditional sweets eaten on this day.