In Japan, May 5th is a national holiday called Kodomo no Hi子供の日, or Children's Day.
Children's Day was designated as an official holiday in 1948. Until then, it was known only as Tango no Sekku端午の節句, a name it also retains to this day, and was a celebration for boys. Tango no Sekku, like the Hinamatsuri, is one of the traditional gosekku五節句, the five seasonal festivals held at the imperial court. Essentially, Tango no Sekku was the counterpart to the Hinamatsuri雛祭り (Doll Festival) in March.
On Children's Day families celebrate the health and happiness of their children. One way they do this by flying large decorative carp-shaped windsocks called koinobori鯉のぼり. Koinobori are often flown outside public buildings and residences and are so popular that they have become synonymous with the festival. Traditionally, black carp represent fathers, red ones mothers, and the smaller carp are children. Smaller indoor versions of these decorations are also available.
Carp are associated with determination, strength, and success. Therefore, koinobori are flown to express families’ desires for their children. Another popular traditional decoration is a model samurai with armor that is placed on a tiered platform. The samurai are often modeled off of popular characters from folktales like Kintaro金太郎 and Momotaro桃太郎. Iris flowers, which typically bloom in early May, are also closely associated with this holiday.
Aside from the decorations, children can enjoy popular sweets like kashiwa-mochi柏餅, which is a rice cake stuffed with sweet bean paste and wrapped in an oak leave, and chimaki粽, which are dumplings wrapped in bamboo leaves.