The succession from Emperor Ōjin to Emperor Nintoku leaves a lasting puzzle between the story of the Nihon Shoki and the Chinese histories of the 5th century.
The Nihon Shoki draws the conflict among brothers over the throne as a story in which loyalty and self-sacrifice restore order.
The Chinese Book of Song, by contrast, records that in the 5th century the Wa kings San, Chin and others sent envoys to China’s southern dynasties, seeking recognition of their royal standing and generalships.
However, which emperors of the Nihon Shoki these kings should be identified with remains under debate.
Laying the two records together reveals a different picture of the 5th-century Wa polity and its royal successions.
According to the Nihon Shoki, after Emperor Ōjin’s death a conflict arose among the princes over the succession. Ōjin is said to have named his son Prince Uji no Wakiiratsuko as heir, but his elder brother Prince Ōyamamori raised troops in opposition and lost his life at the Uji River. Thereafter Uji no Wakiiratsuko and Prince Ōsazaki (the future Emperor Nintoku) repeatedly offered each other the throne; after a long interregnum, Uji no Wakiiratsuko died and Ōsazaki took the throne — so the Nihon Shoki tells it. The account can also be read as a succession tale that turns a bitter conflict among brothers into a story of loyalty and self-sacrifice. There is, however, no contemporaneous source that allows us to confirm directly what political conflict actually occurred.
The Nihon Shoki was completed in 720, several centuries after the age of Ōjin and Nintoku. It is therefore not a contemporaneous record of 5th-century royal succession. Moreover, in the 5th century the Chinese history Book of Song introduces the Wa kings San, Chin, Sei, Kō and Bu. How these Five Kings of Wa correspond to the imperial line of the Nihon Shoki has been studied for a long time. San has been identified as Ōjin, Nintoku or Richū among others, and Chin as Nintoku or Hanzei among others, but nothing is settled. In short, the genealogy of the Nihon Shoki and the king names of the Book of Song cannot simply be overlaid one to one.
The Book of Song records that in the 5th century the kings of Wa sent envoys to the Song dynasty of southern China. In 421 the Wa king San sent envoys, and in 425 San dispatched Sima Caoda to present tribute. Then in 438, the record says, after San died his younger brother Chin took the throne. Chin styled himself “Commissioner with Separate Credentials, Commander of Military Affairs of the six kingdoms of Wa, Baekje, Silla, Imna, Chinhan and Mokhan, Grand General who Maintains the East, and King of Wa,” and asked Song to have the title formally recognized. What Song actually recognized was “General who Maintains the East and King of Wa.” This is an important source showing that the 5th-century Wa polity sought diplomatic recognition of its position within East Asia’s international order.
It cannot simply be declared a “contradiction.” The question is rather how to align the two records. The Nihon Shoki transmits the imperial line of Ōjin, Nintoku, Richū and Hanzei. The Book of Song transmits the names of the Wa kings San, Chin, Sei, Kō and Bu. Researchers have long tried to match them, but there are multiple theories of who San was. The National Diet Library’s overview likewise introduces theories placing San with Ōjin, Nintoku or Richū, and Chin with Nintoku or Hanzei among others. What matters here, then, is not to decide that “one of them is lying,” but to see what the two sources do and do not say about the 5th-century Wa polity.
The Nihon Shoki includes a conflict over the succession set at Naniwa around the time of Emperor Nintoku’s accession. In the reign of Emperor Richū, Nintoku’s successor, his younger brother Prince Suminoe no Ō is said to have rebelled and attacked the Naniwa Palace. Richū fled Naniwa and eventually escaped to Yamato. This story is not necessarily a verbatim record of events. But that Naniwa was remembered as an important place for the polity’s transport, logistics and politics is itself a significant archaeological question. At the northern end of the Uemachi Plateau large warehouse groups were built in the 5th century, and connections to Naniwa’s water transport are considered likely.
The Nihon Shoki and the Book of Song seem to speak of the same 5th-century Wa. Yet what they show is not the same.
The Nihon Shoki A story drawn as: prince → succession to the throne → loyalty → treason → self-sacrifice → a legitimate accession.
The Book of Song A record of diplomacy: king → tribute → official titles → international recognition → military designations.
The Hōenzaka warehouses A material world: goods → water transport → concentration → management → the polity.
Laid together, the three show that the 5th-century Wa polity cannot be understood through a single story.
Stand for a moment at the northern end of the Uemachi Plateau.
This was not only the ground of the Osaka Castle of later ages; long before that, goods gathered here through river and sea transport, and political activity unfolded. The 5th-century Hōenzaka warehouses are thought to have been part of that vast logistics system.
The Nihon Shoki told this age as a story of royal succession. The Book of Song recorded the Wa kings of the same age within diplomacy with China. And archaeology, from the warehouses and terrain remaining on the Uemachi Plateau, seeks out the scale of that politics and logistics.
Three records of the same era. None of them is the complete picture.
That is exactly why walking Naniwa has meaning.
From Emperor Ōjin to Emperor Nintoku. From Emperor Nintoku to Emperor Richū. And on to the 5th-century Wa kings San, Chin, Sei, Kō and Bu.
Lay the story of the succession beside the diplomatic records with China, and the 5th-century Wa polity comes into view as a far more complex world than later genealogies alone would suggest. And one of the stages of that politics and logistics was here, at Naniwa.
The Hōenzaka warehouses. The ancient harbor. The Uemachi Plateau. And Osaka Castle, built upon all of it.
Beneath Osaka’s ground lie not only the stories of kingship, but the traces of the logistics and diplomacy that sustained it.
Continue the story at Osaka Castle.
Three records of the same era — the Nihon Shoki, the Book of Song, and the warehouses beneath the plateau — meet on this ground.
Walk with a historian who lives beside it. Small groups. Osaka Castle every day • English • Max 6 guests
Book Goddess, Queen, Empress, Concubine Call / Text Edward WhatsApp EdwardLast updated: October 2026
Edward Iftody — Osaka Castle’s Resident Historian
Research by Edward Iftody, Osaka-based historian and resident historian at Osaka Castle.
This reconstruction draws on contemporary European accounts, Japanese archaeological research, historical geography, and the surviving physical landscape.