Kodomo no Hi: Carp Streamers, Samurai Helmets and Iris Baths on May 5

In late April and early May, the skies above Japanese homes, rivers and parks fill with swimming fish. Long cloth carp, striped in black, red and blue, billow from tall poles as if the wind were a stream, their open mouths catching air and their tails flipping. Indoors, a small samurai helmet sits on a shelf next to a plate of rice cakes wrapped in leaves. Both are signs that May 5, Kodomo no Hi (Children's Day), is on its way.

Children's Day is a national holiday, and the last day of Golden Week, the cluster of holidays in late April and early May. It is a celebration of children's health and happiness, and of gratitude to mothers. This guide explains where it comes from, what the carp streamers (koinobori) mean, why families display helmets and dolls, which special foods to try, how an iris bath works, and where visitors can see spectacular koinobori displays.

From Tango no Sekku to a National Holiday

Children's Day grows out of Tango no Sekku, one of five seasonal observances adopted from China during the Nara (710 to 794) and Heian (794 to 1185) periods, which fell on the fifth day of the fifth lunar month. It was linked to the start of the rice-planting season, and to the belief that certain plants, especially irises, could drive away evil spirits. In the samurai era it became a celebration for boys, who were encouraged to grow up strong and brave.

In 1948 the Japanese government made May 5 a national holiday dedicated to the happiness of all children and to gratitude toward mothers. Until then it had been known as Boys' Day, the counterpart to Hinamatsuri, the Girls' Day festival of March 3. Today the day is for all children, though many of the old customs, such as carp streamers and helmet displays, still carry traditional associations with boys.

Koinobori: Carp That Become Dragons

The carp-shaped streamers called koinobori fly from poles outside houses and across rivers. They are said to come from a Chinese legend in which a carp that swims up a mighty river and leaps the Dragon Gate waterfall is transformed into a dragon. In Japan, the image became a wish that a child will persevere and succeed. Koinobori are believed to have originated in the Edo period (1603 to 1868) and became colourful in the Meiji era (1868 to 1912).

A traditional set includes a black carp at the top for the father, a red or pink carp for the mother, and smaller carp in blue, green or other colours for the children, usually added in order of birth. The sight of a whole family of carp floating in the wind is one of the loveliest scenes of the Japanese spring.

Kabuto and Kintaro

Inside the house, families often display a kabuto (samurai helmet) and sometimes full miniature armour. This custom, called gogatsu ningyo (May dolls), dates back to the Edo period, when warrior households displayed armour in the season of Tango no Sekku. The helmet is believed to guard against misfortune and stands for strength and courage. Smaller versions have become popular in recent years, partly because they fit more easily in modern homes.

Another favourite figure is Kintaro, a folk hero said to have grown up as a child of extraordinary strength, famous for riding a bear. He is said to have become the warrior Sakata no Kintoki, and dolls of him express parents' hopes that their children will grow up healthy, brave and strong.

Kashiwa Mochi and Chimaki

The special foods of the day are kashiwa mochi and chimaki. Kashiwa mochi is a rice cake filled with red bean paste, and sometimes miso, wrapped in an oak leaf. Oak leaves are seen as a symbol of the continuation of the family line, which makes the sweet a fitting gift to wish for a child's growth and prosperity. The leaf is not eaten; you unwrap the cake before you eat it.

Chimaki are sticky rice dumplings wrapped in bamboo or iris leaves, and they are more common in the Kansai region around Osaka and Kyoto than in Kanto around Tokyo. The tradition came from China, and they are traditionally eaten around the holiday. In late April and early May, you can find both treats at supermarkets, convenience stores and traditional sweet shops.

Shobu-yu: The Iris Bath

Many households take a shobu-yu, an iris bath, on May 5. Fresh stems and leaves of the iris called shobu are placed in the hot bath water, releasing a sharp, herbal scent. The plant has long been used in Japanese folk medicine, and the bath is said to improve circulation and ease aches. Iris leaves are sold at supermarkets in the days before the holiday.

Shobu also has a cultural double meaning. The word sounds like a Japanese expression for valuing martial affairs, so samurai households found the plant especially auspicious. Together these ideas explain why irises appear in the holiday's decorations, foods and bathrooms.

Part of Golden Week

Children's Day is the last of four holidays that make up Golden Week: Showa Day on April 29, Constitution Memorial Day on May 3, Greenery Day on May 4, and Kodomo no Hi on May 5. Many families travel during this stretch, and parks, riversides and theme parks fill with children. Because the weather is mild and fresh green leaves are coming out on the trees, the holiday has a light, outdoor feeling that suits the carp flying overhead.

For visitors, this timing means that the same trip can include the end of cherry blossom season in northern regions, spring festivals, and koinobori displays. It also means that transport is crowded, so reserve seats early, and prepare to be flexible about timing if you travel on the first and last days of the holiday.

Where to See Koinobori

Several towns hold koinobori displays that attract visitors. In Sagamihara, in Kanagawa Prefecture, multicoloured carp have been strung on wires across the Sagami River every year since 1988, donated by local families. In Tatebayashi, in Gunma Prefecture, around 5,000 koinobori are hung above the Tsuruuda River in the lead-up to Children's Day, and in 2004 the city set a Guinness World Record with 5,283.

In Kazo, Saitama Prefecture, a city known for koinobori craftsmanship, a giant streamer 100 metres long and weighing 350 kilograms is flown each May during the city's Peace Festival, hoisted by a crane. These events draw visitors from across Japan. Dates and details change each year, so check local tourism websites before planning a trip.

Plan Your Visit

Children's Day always falls on May 5, so the next one is in 2027. Because it is part of Golden Week, trains, hotels and tourist sites are busy around this time, so book transport and accommodation well in advance. Tatebayashi is about 60 kilometres north of Tokyo; from Tatebayashi Station on the Tobu Isesaki Line it is a walk of about 20 minutes to the river.

Visitors can join in simply: look up at the carp flying in a park, try a kashiwa mochi from a local shop, and look for helmet displays in shops. Be respectful when photographing private homes, and ask before photographing children. Check the local event pages for current dates and any restrictions.