Kodomo no Hi or Children’s Day on May 5 is a national holiday in Japan. This national holiday was designated after the World War II to “respect children’s personalities and promote their well being, while extending gratitude to their mothers.”
Children’s Day has its origin in “Tango no Sekku”, which was declared as a national holiday to officiate public functions on the fifth day of the fifth month each year called Go-sekku (five sekku) (※1) during Edo period. “Tango-no-Sekku” seems to have been launched from old Chinese proverbs, or for coordinating various Japanese traditional festivals assigned altogether to the first Ushi-no-hi (※2) in a month. The day falls on the first day of the long holidays beginning around the end of the month April through early May, when children are entertained by a variety of events everywhere.
On these days of Tango-no-sekku, there are seen various traditional practices with wishes for healthy growth of boys, such as displaying armors and helmets and samurai warrior dolls, putting up carp streamers, taking bath in leaves of the sweet flag or calamus leaves, or eating kashiwa-mochi (rice cakes with bean jam) or chimaki (rice dumplings wrapped in bamboo leaves).

The history of “Chimaki”, which is sticky steamed rice wrapped in bamboo leaves, dates back to the Warring States Period in China 2,300 years ago to commemorate the death of Qu Yuan, a famous patriotic politician, who was trapped in conspiracy and drowned himself in a river where rice dumplings were thrown into for consoling his soul and preventing fish from eating his body. The death of Qu Yuan was on May 5, and it became a practice to eat Chimaki on that day.
In the season plentiful of fresh green in May, people stayed outdoors in paddy fields more often and got infected by skin disease or worms. They tended to fall sick during a change of seasons and took bathing in calamus leaves, Shobu in Japanese, as herbs to take care of their health. During Kamakura period in Japan, samurai families began celebrating the sekku festival in the way aristocrats were doing. This practice called Tango-no-sekku became a widely accepted general practice, particularly because of the word pronounced as Shobu, which is spelled in Japanese differently in two ways, one to mean respect for the way of samurai and the other sweet flag or Acorus calamus.

The custom of putting up Koinobori or carp streamers in the air is said to have begun in Edo period and symbolizes healthy growth of children as used to be practiced traditionally wishing for sound health of children. They are decorated in five colors symbolizing trees, fire, earth, gold and water, and look like carps climbing up against swift stream of a water fall vigorously. It was around the same time, they started to display for decoration Dolls for Boys’ Festival wearing armors and helmets. Kashiwa-mochi (rice cakes with bean jam) wrapped in leaves of an oak tree became popular to be eaten on the day of Tango-no-sekku as an auspicious cake in the hope of well-being of the descendents, since leaves of an oak tree will not fall until a fresh generation of leaves comes out.

They thus started to celebrate Children’s Day with wishes for full respect to the patriotic heroes in the past, care-taking of health during the seasonal changes, and healthy growth of children. The Children’s Day these days is one of the major festivals to represent the Japanese culture, when people pause to review the wisdom of ancestors living wisely in nature and think of families and acquaintances likely overlooked in a busy daily life.

(※1) Sekku means a day to hold an annual festival to celebrate a beginning of a season

(※2). Ushi is one of the twelve zodiac animals, meaning the ox, usually counted as the second among them. The twelve zodiac sings can also represent a year, a ruling hour, and a day.