400px-koinobori4797In Japan the 5th of May is known as Children’s Day or Kodomo no Hi.  Part of Golden Week, it is one of several festivals that celebrated during this time of year.  A national holiday that actually incorporates both Boy’s Day (May 5th) and Girl’s Day (March 3rd), many people still think of it as just Boy’s day.

Many of the traditional symbols of the celebration still revolve around boys, like the displaying of a traditional helmet and samurai dolls representing great warriors of the past.  The most common thing displayed is a carp kite.  The carp is chosen as it is said when one swims against the current it turns into a dragon, symbolising success.  The carp also drives away evil spirts.

Links
Wiki: http://en.wikipedia.org/wiki/Kodomo_no_hi

Others:
http://web.mit.edu/jpnet/holidays/May/kodomonohi.shtml
http://www.essortment.com/all/kodomonohijap_rnsd.htm