A new revelation that Rikikito and Chiho were lovers. Kao and Mahiro search for the location of the letters they exchanged, believing that Chiho may also be involved in the case. Koka heads for a certain place, relying on a small clue from a photograph left on Chiho's mobile phone. Meanwhile, a letter from Rikikito finally arrives at Shang's doorstep. ...... Why did Rikikito kill his sister and parents? After confronting the past and pursuing the truth of the case, what is the shocking truth that she has arrived at?
