Based on the unsolved case special team established in Japan's national police headquarters in 2010, the team consists of the passionate detective Yashiro who is very confident in her physical strength and judo, and the highly intelligent detective Ming Hai who is good at interpreting documents. They belong to the 6th Department of Document Interpretation of the "Special Investigation Countermeasures Room" of the Metropolitan Police Department's First Investigation Division. They are responsible for the document search of unsolved incidents and use text as a starting point to solve unsolved cases.