Satori Kido is a humble detective who doesn't have much of a job or finances. He lives in a converted emergency house that serves as his office. Despite this, there are a few nice things in his life, such as a woman who is his secretary, assistant and informant, performing all these duties for a token payment.

According to an ancient myth, the tablet of the Covenant, written with the pen of God, can reveal the secrets of the universe. It was divided into two parts, and each dynasty - of Light and Shadow - received a fragment.