When Amaterasu-Omikami (the Sun Goddess) was hiding in Ama-no-Iwato (heavenly rock cave), a god gathered many long-singing chickens "Kurokashiwa" and made them crow each other so as to draw the Goddess out of the cave. It is said that after that, Tamanoya-no-Mikoto took this Kurokashiwa and stayed at this place, Osaki. The color of its feathers is beautiful and glossy black tinged with green and purple like metal. Kurokashiwa was designated as National Natural Monument in 1951.