According to the Japanese mythology found in the "Kiki," Amaterasu gave birth to them after she received Totsuka no Tsurugi (The Sword Ten Hands Long) of Susanoo upon making a vow of Amaterasu and Susanoo.
『記紀』の記す日本神話においては、アマテラスとスサノオの誓約において、アマテラスがスサノオの十拳剣を譲り受けて生んだとされている。