When Susanoo (the god of the sea and storms) made a pledge to his sister, Amaterasu (the sun goddess), to prove his sincerity, Amaterasu received a sword from Susanoo and gave birth to three goddesses, known as the 'Munakata-Sanjoshin.'
アマテラスとスサノオの誓約の段で、アマテラスがスサノオの持つ剣を譲り受けて宗像三女神を生んだ。