Eighth film in the Boy Detectives Club series.
| Actor | Role |
|---|---|
 Susumu NamishimaKogoro Akechi | Kogoro Akechi |
 Hitomi NakaharaMariko | Mariko |
 Yūnosuke ItōThe Fiend with Twenty Faces | The Fiend with Twenty Faces |
| HHiroshi YamateKobayashi | Kobayashi |
| YYasushi ObataShimada | Shimada |
 Mitsue KomiyaMitsue | Mitsue |
| SSanae MitsuokaAkiko Shimada | Akiko Shimada |
 Akiko KazamiLady Shimada | Lady Shimada |
 Takashi KandaNot listed | Not listed |
| JJiro TakagiKuroda | Kuroda |
| TTokuro KonishiNot listed | Not listed |
 Jun UsamiKeiichiro Shimada | Keiichiro Shimada |