After the first murder, Shiki's uncle, Director Shindou, is killed as well. The lab is in an uproar. To find out who the killer is, Nishinosono and Saikawa investigate Shiki's room. There they find a robot named Michiru, and a strange message saying "Everything becomes F."

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.