From the Act on National Holidays, the Kyoto National Museum and Koto City.
Japan’s Act on National Holidays was made in 1948. It lists each national holiday with its date and its meaning.
For Children’s Day, on May 5, the law says: to respect the personality of children, to work for their happiness, and at the same time to thank mothers.
Three other holidays in the same law come just before it: Showa Day on April 29, Constitution Memorial Day on May 3, and Greenery Day on May 4.
March 3, the day of Hinamatsuri, is not in the law’s list of national holidays.
Hinamatsuri may seem very old, but according to the Kyoto National Museum, people began to celebrate the day by displaying dolls at the start of the Edo period.
Its origin is Joshi no sekku, a purification event held at the beginning of the third month. Simple dolls made of paper and other plain materials stood in for people. They took on people’s impurities and were then thrown away, for example by being floated down a river.
This custom joined with hiina-asobi, the grand doll play of girls in noble families around the third day of the third month. In the Edo period it changed into rich dolls made for display.
Edo-period hina dolls have names. Some are named after an era, such as Kan’ei-bina and Kyoho-bina. Jirozaemon-bina are said to be named after their doll maker. Kokin-bina were completed in Edo, and Yusoku-bina copy the dress of the court correctly.
May 5 is also Tango no sekku, a yearly event to wish for children’s growth. It was one of the five seasonal festivals set by the Edo shogunate.
People in Edo celebrated it by flying koinobori (carp streamers), placing iris leaves (shobu) on the eaves of their houses, and offering kashiwa-mochi, rice cakes wrapped in oak leaves.
In 2026, the Fukagawa Edo Museum in Koto City, Tokyo, showed a town of the Edo period dressed for Tango no sekku, with koinobori over the streets.
There is no single right answer. Talking it over with someone at home is a good way to learn.