Set in postwar Tokyo in March 1956, private detective Tokisaka Reiji takes an unusual request from a girl in Inokashira Park who wants him to find her true self. His caseload quickly multiplies: Detective Uozumi Kyozo recruits him to help investigate a serial killer targeting young women whose bodies are found mutilated, and the vice principal of Ouba Girls Academy calls him in to investigate two missing students. Posing as a substitute teacher, Reiji re-encounters Kuchiki Toko — his original client — inside the academy. The body count rises, missing persons and unidentified corpses refuse to add up, and the shadow of a nearly identical string of murders from six years earlier makes everything darker and more complicated.