Azusa is a young university teacher who lives next to the academy under the guidance of Hiroki Moriyama. She is an ordinary girl who lives in an apartment filled with memories of her first love. Her home has become a source of inspiration and comfort for her.

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.