An anonymous letter is delivered to the Tokyo Metropolitan Police Department. The letter states that a criminal of a murder case will appear at the countdown party Masquerade Night that will be held at Hotel Cortesia Tokyo. Detective Kosuke Nitta must go undercover and work again at the Hotel Cortesia Tokyo. There, he meets Naomi Yamagishi, who works as a concierge. Without any information about the criminal, except that the person will be in attendance, Detective Kosuke Nitta works feverishly to find the criminal among the 500 attendees.
| Actor | Role |
|---|---|
 Takuya KimuraKosuke Nitta | Kosuke Nitta |
 Masami NagasawaNaomi Yamagishi | Naomi Yamagishi |
 Fumiyo KohinataKazuhiko Nose | Kazuhiko Nose |
 Yoshino KimuraMachiko Sono | Machiko Sono |
 Kumiko AsoMidori Nakane | Midori Nakane |
 Ikki SawamuraAtsuya Kusakabe | Atsuya Kusakabe |
 Ken IshiguroYusaku Ujihara | Yusaku Ujihara |
 Anne NakamuraMayumi Okuda | Mayumi Okuda |
 Saki TakaokaYuri Kaizuka | Yuri Kaizuka |
 Zen KajiharaMasaharu Motomiya | Masaharu Motomiya |
 Masanobu KatsumuraMasaaki Sono | Masaaki Sono |
 Hanamaru HakataMikio Urabe | Mikio Urabe |
 Minami TanakaKumiko Akiyama | Kumiko Akiyama |
 Eisuke SasaiShinjiro Ozaki | Shinjiro Ozaki |
 Ren IshikawaMika Kawamoto | Mika Kawamoto |
 Kaname OukiTaeko Kano | Taeko Kano |
 Ryo IshibashiYasushi Fujiki | Yasushi Fujiki |
 Atsuro WatabeTatsuo Inagaki | Tatsuo Inagaki |