Part of Aoshima Shrine near Miyazaki is a small museum with tableux displaying the cycle of myths set in Hyuga, the old name for what is now Miyazaki. This cycle of myths are now very well known, but historicaly there were many different versions of the myths. It is only in the modern period that one particular version has been established as the "national" myth. For instance, in this first scene we see Amaterasu, commonly known as the Sun Goddess, giving rice to her grandson Ninigi before his descent to Japan to establish rule over the country. However, several versions of the myth say it was not Amaterasu who sent Ninigi, but another kami. Also, on the 3 tables you can see the 3 imperial regalia, but it seems that for some of the ancient, powerful clans there were only 2 regalia.
Reaching Japan Ninigi took himself a wife and she miraculously became pregnant after only one night. Ninigi suspected the father may not be him and his wife was deeply offended by this. She chose to undergo an ordeal by fire to prove she was telling the truth and in the burning birthing hut she gave birth to 2 sons.
There are several stories about the brothers, but one of them has one brother visiting the undersea kingdom of the Dragon King where he is given some powerful magic objects.
After returning from under the sea he marries a princess who gives birth to a baby boy who grows up to be Jimmu, the mythical first "emperor" of Japan and he sets sail from Kyushu to subdue the tribes of Japan and establish the current ruling dynasty.
There are many variations of the stories, including many versions of the characters names and even their genealogies. There is far more diversity in Japanese myths, histories, cultures, and peoples than the monolithic, homogenous versions being spouted and taught today. In the late 19th Century the people of neighboring Kagoshima were horrified to hear that these myths took place in Miyazaki, as they had similar stories that took place in Kagoshima.