In the process of investigating Director Shindou's murder, Nishinosono and Saikawa learn the details of Shiki's multiple personalities and the murder of her parents that took place 15 years ago. The two of them try to figure out what she was thinking in order to find a clue. In doing so, Nishinosono is forced to confront her own past.

Saikawa and Nishinosono return to the camp, putting off trying to find a solution to the case. But they can't stop thinking about it. They go back to the lab and investigate Dr. Shiki's rooms again, where they find a strange number that is a clue.

Saikawa meets Miki, Dr. Magata's sister, and realizes that Dr. Magata's unique mind has remained unchanged since childhood. Meanwhile, Moe experiences virtual reality with the help of another member of the institute's staff, Shimada. As she does, a mysterious voice forces her to confront her own past.