Takashiro recounts the events that took place 1000 years ago, during the Heian period. The Giou clan was a well-known family who directly served the court and was led by 4 high-ranking personages: Ario, Takashiro, Reiga and a girl named Yomi. Reiga was feared and shunned due to his mixed parentage but he was supported by both Takashiro and Yomi. They lived in relative peace until a summons came from the royal court for the Giou clan to exterminate some high-ranking demons that were accidentally summoned...