Tango no sekku (Iris Festival) has been traditionally celebrated in Japan on 5 May as
In 1948, 5 May was designated a national holiday and renamed Children's Day, but it is commonly observed in most families in the traditional way as a festival for boys. (The Girls' festival is March 3, which is called hinamatsuri or the Doll Festival.)
It is customary on this day for families with male children to hoist carp (a symbol of success) streamers (koinobori) from balconies and flagpoles. Koinobori are cloth banners in the form of carp that are flown as an expression
of hope for the male children's health and prosperity. This custom originated during the middle of the Edo period (1600-1868). Based on an ancient Chinese legend that says a carp
swam upstream the river and became a dragon, carp had long been a symbol of success in Japan.
Also as a good omen for the future of their sons, warrior (samurai) dolls, called mushaningyo, wearing kabuto (helmet) and armaments, are decorated inside the house.