"Why...?" At the scene of a serial murder case, Mankin (Kishii Yukino) witnesses Kouki (Shison Jun) standing in front of a woman who has been stabbed all over her body...! Leaving Mankin behind as she aims her camera with trembling hands, Kouki flees. The police put out a nationwide wanted list. Amid a flood of criticism of Mankin for letting the culprit slip away, Kouki, who is on the run, publishes a memoir online, confessing to his crime! Is it true when he says he is the culprit, or...?! Kouki's past is revealed... and finally, the day of the "final murder" arrives!!