In a super-advanced city in the near future where humanoid robot technology is very sophisticated, the boy detective Kenichi is caught up in the conflict as the powerful politician Duke Red, distraught over his child's death, hires a scientist to create a replacement, an exquisitely beautiful sex-changing robot child named Mitchy. Note that this original 1949 manga supplies only part of the plot for the recent Metropolis movie, and does not feature Rock, whose role in the film was adapted from Phoenix, Nextworld and other Tezuka manga.