Spring in Tokyo brings with it an unusual sight.
Look up, and you may notice giant fish-shaped streamers appearing above streets, rivers, and landmarks — colorful carp seemingly swimming through the sky.
In the photo above, taken at the foot of Tokyo Tower, dozens of bright fish flutter together in the wind as if they were alive.
What are these flying carp, and why do they appear every spring?
Carp Swimming Across the Sky
They are called koinobori — carp (koi) streamers traditionally displayed in Japan on May 5th.
Today, May 5th is celebrated nationwide as Children’s Day(Kodomo no Hi), one of Japan’s national holidays. Its origins, however, go back to an older seasonal festival known as Tango no Sekku, which was introduced from China centuries ago.
Originally associated with warding off evil spirits, the festival gradually evolved in Japan into a day dedicated to children — especially boys — and prayers for their health, growth, and future success.
Why Carp Became the Symbol
The answer lies in an old Chinese legend. In a story known as the “carp climbing the waterfall,” a carp that successfully swims upstream and reaches the top of a fierce waterfall transforms into a dragon. This tale is the origin of the expression tōryūmon (the “Dragon Gate”), symbolizing overcoming hardship and achieving great success.
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| “Suidobashi and Surugadai,” from One Hundred Famous Views of Edo (1857), by Utagawa Hiroshige, depicting koinobori flying in the sky |
At the same time, carp have long been admired in Japan for their beauty. Ornamental koi—carefully bred for their vivid colors and patterns—are treasured as living works of art, often kept in garden ponds.
This combination of strength and beauty makes the carp an especially powerful symbol, embodying both resilience and grace.
Samurai Ideals and the Legend of Kintaro
The image of the carp rising toward the sky became closely associated with the hopes expressed during Tango no Sekku. But there is another legendary figure who often appears alongside the carp in traditional Japanese imagery.
His name is Kintaro.
Kintaro is a well-known hero from Japanese folklore, famous for his extraordinary strength from an early age. He is often depicted as a wild child growing up in the mountains, sometimes even wrestling bears. As the story goes, Kintaro eventually grows up to become the samurai Sakata Kintoki, one of the famous warriors of Japanese legend.
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| A Kintaro doll for Children’s Day, at YOSHITOKU in Asakusabashi. |
Because Kintaro came to symbolize strength, courage, and healthy growth, he became a popular figure in Tango no Sekku decorations and artwork. On Children’s Day, families traditionally display dolls of Kintaro as well as miniature samurai armor and helmets.
Kintaro and the climbing carp were sometimes depicted side by side—or even combined in a single scene.
The combination is easy to understand. The carp struggling up a waterfall represents perseverance and the ability to overcome obstacles, while Kintaro represents a child growing strong and eventually achieving great things.
The image above is a traditional Japanese artwork depicting Kintaro together with a carp attempting to climb a waterfall. Such works help show how the symbolism of Tango no Sekku developed beyond the simple display of streamers.
During the Edo period, these ideals spread from the samurai class to ordinary families. Armor, banners, warrior figures, legendary heroes, and eventually koinobori all became part of the visual language surrounding the festival.
From Samurai Tradition to Family Celebration
Modern koinobori are typically arranged to represent a family. A large black carp symbolizes the father, a red carp represents the mother, and smaller carp stand for the children. Above them, colorful streamers called fukinagashi are attached, believed to ward off evil spirits. At the top of the pole, a spinning wind wheel is often added, symbolizing energy rising into the sky. Today, the meaning has broadened—from wishing for boys’ success to celebrating the happiness of the entire family.
Koinobori Today — A Symbol Still in Motion
These symbolic images are not limited to private homes. Across Japan, large-scale displays of koinobori can be seen during the season. Hundreds of carp streamers stretched across rivers or displayed at major landmarks have become a beloved sign of spring.
Carp also appear in modern culture. One well-known example is the professional baseball team Hiroshima Toyo Carp, whose name reflects the same image of perseverance and strength. Fans are often seen waving koinobori flags in the stands as part of their support.
Koinobori swimming through the sky are more than simple decorations.
They represent the hope that children will face challenges, grow strong, and one day rise to great heights. Looking up at them drifting across the Tokyo sky, one might find a quiet reflection of hope for the future.