In this chapter, we learn that the switch demon killed the victim, then mingled with the protagonist and gave him an alibi. In other words, the protagonist is the murderer, and the police have no way to catch him. The protagonist, however, is determined to prove his innocence. He tells the police officer that he knows who the killer is, and that he has proof to prove it. The police officer agrees, but the protagonist refuses to believe him. He says that he already knows the killer's identity, and he wants to know if there is any evidence to support his theory. The officer tells him that there is, but he refuses to admit it, saying that it is useless to deny the truth. He then tells the protagonist that a new discovery has come to light. It turns out that the victim's switch has been pressed down, which means that she is dead. This new discovery is that if the switch is not pressed, everyone will die. This is the first time that the protagonist has solved the puzzle of the switch. He also tells the officer that if he doesn't catch the killer, the other victims will die as well. The cop tells him to check out the diary, which is clearly written by the protagonist's friend, mumujiang. He recognizes the handwriting on the postcard as that of his friend, and it is the same handwriting as in the diary. The policeman says that this must be the handwriting of the dead woman, because she died of an accident, and she was killed by the demon, not by the switch