Kodomo no Hi:
back to the origins
May 5 was originally known as Tango no sekku (端午の節句), the Japanese equivalent of the Double Fifth which is a holiday celebrated in many Chinese households around the world. In 1948, the government changed the official name to Children’s Day.
However, even though May 5 is officially known as Children’s Day, most Japanese still consider and celebrate the “double fifth” as Boy’s Day. This seems only fair as Girl’s Day is celebrated on the “double third” (Hinamatsuri)—though Girl’s Day is not an official public holiday.