Mankoto (Kishi Yukino) learns that the "suspicious man" who has been appearing at the scene where the fifth Horus Eye Murder is likely to occur is Hiroki's (Shison Jun) father, Kanji (Hagiwara Masato). Could Kanji be the Horus murderer? Thinking of Hiroki's complicated feelings, Mankoto is even more passionate about solving the case. Meanwhile, while the police are pursuing Kanji as a key witness, Masamasa (Shirasawa Jin) cannot wipe away his doubts about Hiroki... On the fateful day of May 5th, Mankoto, who is staking out the scene, encounters a man in a black raincoat --!?
