Who Is Ryujin? The Dragon King of the Sea, From Chronicle to Rain Rite
Ryujin is the dragon king of sea and rain in Japanese belief, built from a native water snake, Chinese dragons and Buddhist rain kings. The Kojiki's sea palace has a sea kami and no dragon; the earliest dragon we could verify is in the Nihon Shoki.
The five clues from the game
From faint to clear: each clue is a little darker than the last.
- This being belongs to water: fishers ask it for full nets and calm seas, and farmers for rain.
- Chamberlain's Kojiki translation describes a sea palace built like fishes' scales, which later tradition links to this being, although the chronicle does not name it.
- In the main account of the Nihon Shoki, the sea deity's daughter changes during childbirth into the creature this being is usually pictured as.
- A Buddhist painting of the mid-twelfth century at Kongobuji shows a deity of this kind as a Tang official on a cloud, with a snake's tail behind his robes.
- Fishermen thought it taboo to drop metal into the sea, lest they anger this being, who is celebrated as the kami of a palace beneath the waves.
Three ways to read this scroll
Living practice
Water and rain rites continue at shrines such as Kifune, where the rain kami Takaokami is honored and one theory calls it a dragon god. We could not verify current festivals held under the name Ryujin itself.
Folk tradition
Fishers prayed to the sea kami for full nets and calm water, kept a taboo against dropping metal into the sea, and told tales such as Urashima Taro and Ryugu Doji, where a sea kami meets humans.
Literary work and art
The Kojiki (712) tells of a sea palace and tide jewels without a dragon. The Nihon Shoki (720) has the sea kami's daughter change into one, and a mid-twelfth-century painting at Kongobuji shows a Buddhist rain king.
Many tellings place the sea's dragon king in a palace beneath the waves, with a princess, a banquet and a pair of tide jewels. Ask where that palace is first written down, and the answer is surprising. The oldest sea palace in Japanese writing belongs to a sea deity who has a daughter, a visiting prince who lost his brother's fishhook, and a sea bream with the hook stuck in its throat. The Kojiki does not call him a dragon king. The dragon arrives from several directions at once: a native water snake, the dragon of China, and a Buddhist rain king. This page follows each path and keeps worship, folk custom and tale in separate drawers.
The sea palace in the Kojiki
The Kojiki, a court chronicle completed in 712, tells of two brothers. The younger, Hoori, swaps his hunting gear for his elder brother's fishhook and loses it at sea. The kami Shiotsuchi sets him in a tightly woven craft, which Chamberlain calls a boat and the Kokugakuin encyclopedia calls a basket. In Chamberlain's 1882 translation, the kami describes what he will find:
there will appear a palace built like fishes’ scales,—which is the palace of the Deity-Ocean-Possessor.
Basil Hall Chamberlain, trans., Kojiki (1882), Section XL.
The Deity-Ocean-Possessor is Watatsumi, the sea kami. The encyclopedia explains the name as "holder of the sea" and says both chronicles record three Watatsumi deities, born when Izanagi purified himself after leaving Yomi. Hoori marries Watatsumi's daughter Toyotama-hime and stays three years. The lost hook turns up in a sea bream's throat. He leaves with two jewels, one to raise the tide and one to lower it. Later he peeps at his wife giving birth on the shore, and she closes the passage between sea and land.
Notice what is not there. The Kojiki, as Chamberlain translates it, has no dragon in this story. Toyotama-hime becomes a wani, which Chamberlain renders as crocodile and the encyclopedia thinks was probably a shark.
A dragon in the second chronicle
The Nihon Shoki, laid before the court in 720 according to W. G. Aston's reading of a Heian commentary, tells the birth scene differently. In Aston's 1896 translation of the main account, the princess has changed into a dragon when her husband looks in (vol. 1, p. 95). So the earliest dragon we could verify in this story belongs to the sea deity's daughter, not to a king.
Aston added a note on the word wani. Citing Satow and Anderson, he said it is usually drawn as a dragon in art. Since Toyotama-hime was the Sea-God's daughter, he suspected that the Sea-God was one of the Dragon-Kings known in Chinese and Korean tales, who live in palaces on the sea floor. He also quoted Chamberlain:
the whole story of the Sea-God’s palace has a Chinese ring about it, and the cassia-tree mentioned in it is certainly Chinese.
W. G. Aston, trans., Nihongi (1896), vol. 1, pp. 61-62, note 8, quoting B. H. Chamberlain.
Treat this as a nineteenth-century scholars' comparison: a lead about where the motif may come from, not a Japanese tradition and not proof.
Dragon, snake and water kami
The Kokugakuin encyclopedia describes a broader faith. Chinese dragons influenced Japan, it says, but the Japanese dragon as an object of worship was a deified snake, a symbol of the water kami. The words ryujin, ryuo and ryugu, meaning dragon kami, dragon king and dragon palace, all turn up. Because water feeds the rice, prayers for rain were made at rivers, swamps, ponds and deep pools thought to be the homes of the dragon kami. Farm rites used a straw rope shaped like a dragon. The dragon kami was also tied to Raijin, the thunder kami, and was thought to rise to heaven when a tornado formed.
The sea kami, imagined beyond the horizon, became a frequent stand-in for the dragon kami. Fishermen asked for full nets and calm water, and held festivals with names such as inlet festival, beach festival and tide festival. One belief grew from the snake: metal was thought to cancel a snake's power, so dropping metal into the sea was taboo, lest the snake kami be angered.
A drought, a garden and a rain king
A different strand is Buddhist. JAANUS, the art-historical dictionary hosted by Columbia University, says that in 824 the monk Kukai prayed for rain at Shinsen-en, a garden in the imperial palace at Kyoto. The dragon king Zennyo Ryuo is said to have appeared on Mount Atago and brought rain. The earliest picture of the event that the dictionary names is a mid-twelfth-century painting by Jochi at Kongobuji on Mount Koya. It shows the deity as a Tang official riding a cloud, holding a jewel on a tray, with a snake's tail showing behind his robes. That is about three centuries after the event, so we treat the rain prayer as a tradition, not a dated record.
Shinto rain rites stand beside it. Kifune Shrine in Kyoto honors Takaokami, also called Kuraokami. The shrine says the chronicles record this water kami as born when Izanagi killed the fire kami, and that no record of its own founding survives. It adds that one theory calls Takaokami the "Dragon God of the Mountain," though shrine records say the two names are one kami. Across generations of imperial courts, the shrine says, black horses were offered in droughts, and white or red horses when rain would not stop.
Reading the records: who wrote what, and when
| Record | Date | Kind | What it shows |
|---|---|---|---|
| Kojiki, sea-palace episode | Completed 712 | Court chronicle | Watatsumi, Toyotama-hime as a wani |
| Nihon Shoki main account | Laid before the court 720 | Court chronicle | The princess changes into a dragon |
| Aston's note | 1896 | Translator's commentary | Comparison with Chinese Dragon-Kings |
| Painting of the rain prayer | Mid-12th century | Buddhist painting, Kongobuji | Zennyo Ryuo as a Tang official with a snake's tail |
| Kifune Shrine | Founding unrecorded | Living shrine | Rain kami, horse offerings, a dragon theory |
| Tide-jewel sculpture | Meiji period | Museum object, Cleveland | Tide jewels and the Dragon King blended |
The Cleveland Museum of Art notes that its Meiji sculpture mixes an early legend of a sea god with two tide jewels, other legends in which the jewels belong to the Dragon King, and Chinese tales of dragons who make rain with pearls. It was made to appeal to collectors abroad, so it shows how the strands were blended, not where they started.
How to tell a tale from a practice
- Check the name. Watatsumi, Zennyo Ryuo, Takaokami and Ryujin belong to different strands.
- Check who acts. A prince in a chronicle is literature. Fishers keeping a taboo or priests offering horses are custom.
- Check the kind and age of the record. A chronicle, a painting, a shrine page and a museum object each answer different questions.
- Check the tense. The encyclopedia speaks of fishers' festivals in the past tense, so we could not verify which ones still run under this name.
Common mix-ups
"The Kojiki has a dragon king called Ryujin." It has a sea kami, Watatsumi. The name Ryujin does not appear in the episode.
"Toyotama-hime was a dragon." In the Kojiki she becomes a wani. The dragon is the Nihon Shoki's version.
"Watatsumi and Ryujin are the same." The encyclopedia says the sea kami became a common stand-in for the dragon kami. That is a later equation, and sources differ on how tight it is.
"The dragon is simply Chinese." The encyclopedia says the object of faith was a deified snake, with Chinese influence added.
"The 824 rain prayer is a dated event." JAANUS says the dragon king "is said to have" appeared. Treat it as tradition.
"Tide jewels belong only to the dragon king." The Kojiki gives them to the sea kami, and Cleveland notes that other legends give them to the Dragon King. The encyclopedia lists Urashima Taro among the tales in which a sea kami meets humans.
A sea kami in a chronicle, a snake revered at a pond, a rain king painted on silk and a jewel carved for a collector are different things sharing one name. Keeping them apart is the honest way to read them.
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Frequently asked questions
Is Ryujin in the Kojiki?
Not by that name. The Kojiki tells of a sea palace belonging to the sea kami Watatsumi, whose daughter Toyotama-hime marries the prince Hoori. In Chamberlain's translation she turns into a crocodile-like wani, not a dragon. The Nihon Shoki's main account, in Aston's translation, says she changed into a dragon.
Are Watatsumi and Ryujin the same being?
Not exactly. Watatsumi is the sea kami of the chronicles. The Kokugakuin University encyclopedia says the sea kami became a common stand-in for the dragon kami in later belief. That is a later equation, and sources differ on how tightly the two are joined, so it is safer to read them as separate strands.
Why did Japanese fishers avoid dropping metal into the sea?
According to the Kokugakuin encyclopedia, metal was believed to cancel the magical power of a snake, which led to the idea of avoiding acts that would anger the snake kami. Because the snake, the dragon kami and the sea kami were treated as equivalent, fishermen held it taboo to drop metal into the ocean.
What is the story of Kukai and the rain prayer at Shinsen-en?
JAANUS says that in 824 Kukai prayed for rain at Shinsen-en, a garden in the Kyoto palace, and that the dragon king Zennyo Ryuo is said to have appeared on Mount Atago and brought rain. The earliest picture it names is a mid-twelfth-century painting at Kongobuji, so the prayer is best read as a tradition, not a dated record.
In which tales does a sea dragon king appear?
The Kokugakuin encyclopedia names Urashima Taro and Ryugu Doji as folk tales in which a sea kami meets humans. The Cleveland Museum of Art adds that some legends give the tide-controlling jewels to a Dragon King who rules from a palace beyond or beneath the sea. The Kojiki's own sea palace belongs to Watatsumi.
Sources
Opened and read by our team. Checked November 9, 2026.
- Ryujin shinko (Encyclopedia of Shinto entry), Kokugakuin University, Encyclopedia of Shinto (Iwai Hiroshi). Dragon faith as a deified snake and water kami, rain prayers, fishers' festivals, metal taboo, folk tales. Checked November 9, 2026.
- Hohodemi (Encyclopedia of Shinto entry), Kokugakuin University, Encyclopedia of Shinto (Mori Mizue). Hoori's visit to the sea palace, the lost fishhook, tide jewels, Toyotama-hime's transformation. Checked November 9, 2026.
- Watatsumi (Encyclopedia of Shinto entry), Kokugakuin University, Encyclopedia of Shinto (Nakayama Kaoru). Watatsumi as the sea kami, three Watatsumi deities, meaning of the name as holder of the sea. Checked November 9, 2026.
- Kojiki (Chamberlain, 1882), Section XL: The Palace of the Ocean-Possessor, Basil Hall Chamberlain, translator; Wikisource transcription. Quoted description of the sea palace, tide-flowing and tide-ebbing jewels, the bream and the hook. Checked November 9, 2026.
- Nihongi: Chronicles of Japan from the Earliest Times to A.D. 697, vol. 1, translated by W. G. Aston, Japan Society, London, 1896 (scan on Internet Archive). Dates 712 and 720, Toyotama-hime as a dragon on p. 95, Aston's note on Dragon-Kings on pp. 61-62. Checked November 9, 2026.
- Zennyo Ryuo (JAANUS entry), JAANUS, Japanese Architecture and Art Net Users System, hosted by Columbia University. Kukai's rain prayer of 824 at Shinsen-en, Jochi's mid-twelfth-century painting at Kongobuji. Checked November 9, 2026.
- Tide-Changing Jewel with Dragon (okimono, Meiji period), Cleveland Museum of Art. Museum note on tide jewels, the Dragon King's palace, Chinese rain-making dragons, Meiji export taste. Checked November 9, 2026.
- About Kifune Shrine, Kifune Shrine, official website. Takaokami and Kuraokami, unrecorded founding, a dragon-god theory, horse offerings for rain. Checked November 9, 2026.
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