One day, Ninigi-no Mikoto (ににぎのみこと) met a rare beauty at Kasasano Misaki (かささのみさき). Ninigi fell in love with the beauty at the first glance.
Ninigi asked her who her father was. She replied that she was a daughter of Ooyamatsumi-no Kami (おおやまつみのかみ). She also told him that her name was Konohanasakuyabime or Kamuatatuhime (かむあたつひめ). Ninigi asked if she had her siblings. She told him that she had a sister called Iwanagahime (いわながひめ).
Ninigi immediately courted her. Konohana told him that Ninigi should ask her father for the permission.
Ninigi sent his messenger to Ooyamatsumi right away. Ooyamatsumi was delighted in Ninigi’s proposal so much that he even offered Iwanagahime in addition to Konohanasakuyabime with lots of brides’ outfits. In ancient times, there were cases when sisters married one man because a marriage was widely considered to be between two families, instead of two individuals.
Unfortunately, Iwanagahime was so homely that Ninigi didn’t accept her as his wife. Poor Iwanagahime had to go back home against her will, which tremendously disappointed Ooyamatsumi. Frustrated Ooyamatsumi, at the sight of Iwanagahime, said, “Great grief! There was the reason that I sent them to Ninigi at the same time. Iwanagahime was supposed to make Ninigi immortal while Konohanasakuyabime to make him prosperous in generations. That was my strong wish, which Ninigi ruined. Now that he kept only Konohanasakuyabime, he will be prosperous but he will not enjoy eternal life!”
Due to this wrong decision of Ninigi, Japanese emperors have become mortal since then though they are offsprings of the Heavenly Gods.