The police arrive and their investigations reveal the baumkuchen was cut evenly into eight pieces and that only one of the piece was poisoned. As police interview the suspects while the widow, Serika Wakamatsu, is excluded since she was never close to the Baumkuchen tray. Meanwhile, the police detectives in Nagano reveal to Heiji that Wakamatsu's killer reorganized the bathroom tiles to hide the dying message; The tiles used the crazy diamond optical illusion giving the impression that it ...