Yesterday May 5th was Children's Day in Japan.
When families celebrate the healthy growth and happiness of children. It became a national holiday, but it has been a day of celebration in Japan since ancient times.
The fifth day of the fifth month was traditionally called 'Tango no Sekku' (端午の節句） and was a festival for boys.
Girls have their own festival, called 'Hina Matsuri' or'Doll Festival'（ひな祭り）.http://ameblo.jp/yunjoohiang/day-20080307.html
On Children's Day, families with boys fly huge carp-shaped streamers 'koinobori'（鯉のぼり） outside the house and display dolls of famous warriors and other heroes inside. The carp was chosen because it symbolizes strength and success; according to a Chinese legend, a carp swam upstream to become a dragon.
In recent years, as more people have moved into apartments and smaller houses, the carp streamers have also gotten smaller, and there are now miniature versions that are decorated indoors.
Also on this day, families often take baths sprinkled with iris leaves and roots. This is because the iris is thought to promote good health and ward off evil. Rice cakes wrapped in oak leaves and filled with sweet bean paste, called 'kashiwamochi',（柏餅）are also eaten.