こどもの日 (hiragana: こどものひ, romaji: Kodomo no Hi) in Japan is celebrated on the 5th of May. Is a Japanese national holiday part of the Golden Week. It is a day set aside to respect children’s personalities and to celebrate their happiness. It was designated a national holiday by the Japanese government in 1948. It has been a day of celebration in Japan since ancient times.
It was originally exclusively male celebrating boys and recognising fathers, but has since been changed to include both boys and girls, as well as recognising mothers along with fathers.
On this day, families raise the carp-shaped “koinobori” flags (carp because of the Chinese legend that a carp that swims upstream becomes a dragon, and the way the flags blow in the wind looks like they are swimming), with one carp for the father, one for the mother, and one carp for each child (traditionally each son). Families also display a “Kintarō” doll usually riding on a large carp, and the traditional Japanese military helmet, kabuto, due to their tradition as symbols of strength and vitality.
Mochi rice cakes wrapped in kashiwa (oak) leaves—kashiwa-mochi (mochi filled with red bean jam) and chimaki (a kind of “sweet rice paste”, wrapped in an iris or bamboo leaf)—are traditionally served on this day.
To take a bath with iris leaves on May 5th. Pu iris leaves into the bath and then take a bath it’s believed to ward off misfortune. They’re often sold in supermarkets during that time.