When a strange group of men attempt to kidnap Atsuko Fukune, a dancer at a club, she seeks the help of Mamiya Mugen, a famous detective - who also happens to be a child. When it turns out that other girls have gone missing, Mamiya, with the help of his butler Alucard, springs into action to solve the mystery.
| Actor | Role |
|---|---|
 Keiko TodaMamiya Mugen (voice) | Mamiya Mugen (voice) |
 Hiroko EmoriAtsune Fukune (voice) | Atsune Fukune (voice) |
 Junpei TakiguchiInspector Edogawa (voice) | Inspector Edogawa (voice) |
 Joji YanamiDoctor (voice) | Doctor (voice) |
| MMiyoko AobaSakura Satomi (voice) | Sakura Satomi (voice) |
 Ichiro NagaiDr. Tomino (voice) | Dr. Tomino (voice) |
 Banjo GingaAlucard (voice) | Alucard (voice) |