One of the best in the series, "透明怪人" mixes traditional troupes of the "少年探偵団"'s series with H.G. Wells's "The Invisible Man". Here we have a mysterious invisible person who, pretty soon, we discover is a thief and a trickster, facing off with the Boy Detectives Club and its president, Kobayashi-kun. However, instead of centering on the detectives, the book starts with its focus on the invisible man and a journalist that follows him. Yes, there are a couple of boys that get entangled in the invisible man's 'nefarious' plans, but they are secondary characters to the real main character. And Edogawa, again, as always, creates a fun (the sense of humor and tongue-in-cheek approach is pervasive) but light story, with a couple of nice tricks, some well developed set-pieces and with his amazing capacity for dread and darkness (toned down compared with his 'for adults' works). The supposedly hero of the series, the super famous detective Akechi Kogorō takes, as in almost all of the novels in the series, a secondary, 'second half of the book appearance but basic for the resolution of the story', part.
If you enjoy the series, you will enjoy this. If you prefer your Edogawa 'real dark', this may not be for you.
The best: how Edogawa mixes "The Invisible man" with his "The Boy Detectives Club" series
The worst: more of the same, in particular when it comes to the resolution
Other reads: the first in the series ("怪人二十面相") is probably the best of the ones I've read, even though all of them are fun (even if kind of repetitive and taking many ideas and twists from his novels for adults); "The Three Investigators" is another series with common points with this one, and any other series with youth sleuths out there