Jimmu Tennô is said to have been the youngest of four brothers, who lived in the province of Hiuga.
When he reached the age of forty-five, he addressed his elder brothers and his children, saying: "Of old, our Heavenly Deities, Taka-mi-musubi, and Oho-hiru-me, gave this land of fair rice-ears of the fertile reed-plain to our Heavenly ancestor, Hiko-ho no ninigi. Now I have heard from the old sea-father that in the east there is a fair land encircled by blue mountains. Let us make our capital there." So on the fifth day of the tenth month of the year corresponding to B.C. 607[86] they sailed northwards, and passing through the Bungo Channel arrived at Usa,[87] near the Strait of Shimonoseki.
At this time there appeared the ancestors of the local chieftains of Usa, named Usa-tsu-hiko and Usa-tsu-hime, who built a palace raised on one pillar on the bank of the River Usa, and offered them a banquet. Then, by imperial command, Usa-tsu-hime was given in marriage to the Emperor's attendant minister Ama no tane, the remote ancestor of the Nakatomi House.
Proceeding on their voyage eastwards through the inland sea, Jimmu and his brothers arrived at the entrance of the river which falls into the sea near Ôsaka. Here they encountered a swift current, for which reason that place was called _Nami-haya_ (wave-swift) or _Nami-hana_ (wave-flower) of which _Nani-ha_ (a later poetical name of Ôsaka) was thought a corruption.[88]
The first encounter of Jimmu's forces with the inhabitants of this part of Japan was not to their advantage:--
"_The Emperor was vexed, and said: 'I am the descendant of the Sun-Goddess, and if I proceed against the Sun to attack the enemy, I shall act contrary to the way of Heaven. Better to retreat and make a show of weakness. Then sacrificing to the Gods of Heaven and Earth, and bringing on our backs the might of the Sun-Goddess, let us follow her rays and trample them down.'_"
Subsequently he proceeded southwards to Kumano, in the province of Kiï, where he embarked with his army in the "Rock-boat of Heaven." In the midst of the sea they suddenly met with a violent wind, and Jimmu's ship was tossed about. Then Ina-ihi, one of Jimmu's elder brothers, exclaimed, "Alas! my ancestors were Heavenly Deities and my mother was a Goddess of the Sea. Why do they harass me by land, and why, moreover, do they harass me by sea." So he drew his sword and plunged into the sea, where he became changed into the God Sabimochi.[89] Another brother of the Emperor, Mike Irino, also indignant at this, said: "My mother and my aunt are both Sea-Goddesses: why do they raise great billows to overwhelm us?" So treading upon the waves, he went to the Eternal Land.