Imagine a world where coal is the only fuel source and steam technology is highly advanced; in this world lies a fog-covered city known as Steam City. And under the cover of the mist, evil people use megamatons – steam-powered robots – to wreak havoc on the townspeople. Narutaki, a teenage detective with a brilliant mind, is the only person who can put a stop to these villains. With the aid of the nurse Ling Ling and the megamaton Goriki, Narutaki will stop at nothing to guarantee the safety of Steam City and all of its inhabitants!
Shinichi Kudo is a famous teenage detective who idolizes Sherlock Holmes and solves difficult cases with ease. One day, after a fun day at the theme park with his childhood friend Ran, Shinichi witnesses something suspicious and is knocked unconscious. What’s worse, he’s forced to take a deadly, experimental drug that shrinks his body to the age of seven. To protect himself and his loved ones from those who may want to finish the job, Shinichi dons the new name Conan Edogawa and moves in with Ran, whose father is a famous detective, in hopes of closing cases that can lead him to the men in black. But little does Shinichi know just how dangerous these men, and their cause, are...
The mystery of "The Blade Children" is a secret which has remained well-hidden, and has cost some their lives. After Narumi Ayumu's brother disappears in a search for the answer, Narumi is forced to unravel this mystery for himself. Join him in his investigation which will lead him to the secrets of the Blade Children, and to tests of skill which may prove to be fatal.
If you liked Steam Detectives then you will also like Spiral because they are similar and both tries to solve a big mystery. The main characters are teenagers and both series have a girl who helps the detective.