After waking up from a month-long coma due to injuries sustained in a reckless, heated investigation, detective Yashiro Tomo quickly returns to work at the Tokyo Metropolitan Police Department. She is ordered to transfer from the First Investigative Division's Violent Crimes Unit to the Sixth Special Investigations Unit. Located in the basement, it is in charge of deciphering documents of unsolved cases. Despite Tomo's bewilderment, she begins work in her new postalong with a brusque senior detective Narumi Risa who is called the expert of document deciphering for her unusual ability to predict the personality and thoughts of a writer from writings. However, the reality is that this kind of work is nothing more than that of a "storekeeper" of investigation materials—Ahloyz