Reyvateils, who can generate supernatural power by singing songs (song magic), were origianlly developed about 700 years ago and spread across the entire world. The Kurogane Laboratory was one such entity that contributed to that technology. However, the Reyvateils, who opposed their inhumane treatment by humans in Kurogane Laboratories, started to rebel against them. Soon after, the chairman of the Kurogane Laboratory, Kurogane, died, triggering a major revolt, resulting in the establishment of a Reyvateilic nation--this is the predecessor of Clustania.