The Story of Emperor Jinmu’s Eastern Expedition

At a Glance

Central figures: Emperor Jinmu (Kamuyamato Iwarebiko), first emperor of Japan and descendant of Amaterasu; his brother Itsuse-no-Mikoto; the chieftain Nagasunehiko; and Takakuraji, the god of earthly rule.
Setting: Kyushu, the Seto Inland Sea route, and the Kinki region - particularly the Nara Basin and the Kashihara Plain - during the mythic age of Japan’s founding, as recorded in early Yamato tradition.
The turn: After Itsuse-no-Mikoto is wounded fighting eastward, Jinmu interprets the defeat as opposition to Amaterasu’s will and reroutes the entire expedition to approach from the west, aligning his advance with the sun’s path.
The outcome: Jinmu defeats Nagasunehiko with the aid of a golden kite sent by Amaterasu, receives the Sacred Mirror from Takakuraji, and establishes the Yamato dynasty with its capital at Kashihara.
The legacy: Jinmu is enshrined at Kashihara Jingu Shrine in Nara Prefecture, and his founding of the dynasty is commemorated as Kigensetsu, the Foundation Day of Japan, traditionally dated to 660 BC.

Kamuyamato Iwarebiko was forty-five years old when he led his forces out of Himuka in Kyushu. Behind him lay the lands his family already held. Ahead lay everything else - the dense forests and mountain passes of the interior, the hostile tribes who had no intention of surrendering them, and a mandate he understood to come not from ambition but from Amaterasu herself, the sun goddess from whom his blood descended. His great-grandfather Ninigi-no-Mikoto had been sent down from the heavens to govern the earthly realm. The throne Jinmu was going to claim was not something he was taking. It was something he was returning to its proper place.

He set out with his brothers and a large company of warriors, moving by sea along the coasts, then pressing inland.

The Wounding of Itsuse-no-Mikoto

The first serious resistance came near present-day Osaka. Jinmu’s forces drove east into the rising sun, and the battle went badly. Itsuse-no-Mikoto, Jinmu’s brother, took an arrow and did not recover from the wound. He died before the campaign could continue.

Jinmu read the defeat carefully. They had been marching against the east - against the direction from which Amaterasu’s light comes. To press a sword toward the sun is to press it toward the goddess herself. The loss of Itsuse-no-Mikoto was not simply a military setback. It was a sign that the approach was wrong.

Jinmu ordered the expedition to turn. Instead of forcing eastward into the sun, they would come around - south, then up through the Kii Peninsula - so that when they advanced on the Kinki heartland, the sun would be at their backs. Amaterasu’s light would fall on their faces and blind no one on Jinmu’s side. The change cost time. It meant longer roads and harder country. Jinmu held to it.

The Golden Kite and Nagasunehiko

Nagasunehiko was waiting for them. His name means “Long-legged Man,” and he was the most formidable chieftain in the region - a leader of substantial forces who knew the Yamato basin the way Jinmu knew the shores of Kyushu. He had no intention of yielding, and his warriors fought accordingly.

The battle stalled. Jinmu’s forces could not break through. Nagasunehiko’s men held their ground and then pushed back.

Jinmu prayed.

What came in answer was a golden kite. It descended from the upper air and landed on the tip of Jinmu’s bow. The light it gave off - bright, almost insupportable - fell across Nagasunehiko’s ranks. His warriors could not see. Their formations broke. Jinmu’s forces pressed through the gap and the battle turned completely.

Nagasunehiko’s army was defeated. The road into the Nara Basin was open.

The Sacred Mirror and Takakuraji

The Kashihara Plain lay in a broad depression ringed by the Yamato mountains - level ground, well-watered, the kind of place where a capital could take root. Jinmu’s forces had reached it, but the final confirmation of his right to rule came not through combat.

Takakuraji, the god of earthly rule, appeared to Jinmu in a vision. He came bearing the Yata no Kagami - the Sacred Mirror, one of the Three Sacred Treasures - and presented it directly to Jinmu. The mirror was not simply an object of value. It was the emblem of Amaterasu’s direct authority, a physical sign that the sun goddess endorsed what Jinmu was doing. No sword, no disputed lineage, no political argument carried the same weight as this.

The mirror passed from Takakuraji’s hands to Jinmu’s. The divine endorsement was given. What remained was the act itself.

The Founding at Kashihara

Jinmu declared the founding of the Yamato dynasty on the Kashihara Plain and established his capital there. The date the tradition holds is 660 BC - the first year of what would become the Kigen calendar, Japan’s count of years from the founding reign.

The capital at Kashihara was not chosen arbitrarily. The Yamato mountains enclosed it on three sides. The plain was fertile. And it was understood to be the spiritual and geographic center of the nation - the axis around which the rest of the archipelago properly ordered itself. To rule from Kashihara was to rule from the place the gods had arranged for the throne.

The dynasty Jinmu established did not end with him. The imperial line that traces its origin to that declaration on the Kashihara Plain has continued, in one form or another, ever since. Every emperor after Jinmu held authority understood to descend from Amaterasu through Ninigi-no-Mikoto and through the founder who brought his forces around to face the right direction, who prayed when his armies were failing, and who received a mirror from a god in a vision on the plains of Yamato.

Kashihara Jingu and What Remained

Jinmu is enshrined today at Kashihara Jingu Shrine in Nara Prefecture. The shrine stands near the site traditionally identified as his palace. On Kigensetsu - Foundation Day - the commemoration of that first year returns: the founding act, the divine ancestry, the expedition’s end in a valley ringed by mountains.

The golden kite that landed on his bow became an emblem. The Sacred Mirror became one of the three objects at the center of imperial regalia. And Nagasunehiko, the Long-legged Man who made Jinmu fight for every mile of the Nara Basin, is simply gone - his name surviving only in the story of his defeat.

What the expedition left behind was not just a dynasty. It was a way of understanding what the dynasty was: not a family that had won by force, but a lineage that had aligned itself with heaven, turned when heaven required turning, and received its authority from the hand of a god.