Knocking on the Door of the Secret Chamber (2 Volumes in Total)

I thought it was a secret room murder, but a big hole opened in the wall. What was the murderer's purpose? A young woman was murdered in a park. Why did the "impossible" watch she was wearing stop at a strange time? The female high school student who entered the underground passage did not come out from the other side and suddenly disappeared... Six clueless cases were solved through seamless cooperation and tacit understanding between two young detectives - Katarashi Hyōsame, who specializes in motive analysis, and Gotemba Kaori, who focuses on the study of crime techniques!