The Key of Oracles is a spell book that Sadako discovered while researching in the world of the living during the three years time skip in her bio. The books origins are a mystery, Sadako however believes that the spells & rituals within the book were once practiced by humans long before she was born and that they may be simular to Kidō. The book is a guideline for channeling and manipulating Reiatsu. It often refers to Reiatsu as “magic” and Sadako assumes that this was how humans perceived it hundreds of years before. The diagrams or sigils used in the book are instruments for channeling Reiatsu in different ways. It also gives detailed information about the spirit world and how to connect with it. During Sadako’s studies she learned that in the past the humans were much more spiritually aware and practitioners of the black arts described in the book were able to interact with the spirit world with considerable effortlessness.