In medieval Japan, cults had spread their influence. They made a contract with Demons and from that the mysterious "Dagger" was born. The dagger could somehow transcend and transform those who impaled their hearts with it. After that, in the Meiji era of Japan when the Japanese were beginning to be more open towards foreigners, Rena Retta and Kamiyama Retta cross paths and a cursed destiny awaits Rena and his descendants for years too come.