- 1. The Scarlet Diamond
- 2. A Fight in the Dark
- 3. The Riddle of the Beard
- 4. The Secret of the Skull
- 5. The Wisdom of a Fool
- 6. Ultraviolet Rays
As Kosakai explains in the preface, the stories are meant to encourage young readers to learn about science by showing them that science is interesting. In that respect, I think he keeps his promise fairly well. Almost all the stories have a large scientific element, generally well integrated into the story. Only once or twice did it feel like it was getting a bit bogged down in exposition. This scientific character may well remind you of R. Austin Freeman's Dr. Thorndyke stories.
Some people find the Dr. Thorndyke stories a little dry. I do too, but generally in a positive way. The Boy Science Detective stories are also a little drier than say EDOGAWA Rampo's boy detective series. The criminals in Kosakai's series are just dull and often not especially competent professional criminals, not flamboyant masterminds; but Kosakai does not forget that he has young readers who want to be entertained. While the villains are generally unremarkable, his child detective is allowed to surprise the onlookers again and again.
The hero is TSUKAHARA Toshio (塚原俊夫), a twelve year old genius, whose rich parents and richer uncle have fitted him out with his own laboratory, from which he takes cases as a private detective. The narrator is his bodyguard and assistant OONO (大野), a young judo expert (whom Toshio mostly calls niisan, 'big brother'). This is an early instance of a constellation most famous from Rex Stout's books, where Archie Goodwin does the more dangerous and active work, Nero Wolfe does the intellectual part. Toshio is pretty active himself, but any violence gets deputed to Oono. Apart from Oono, the most important recurring character is Detective Oda of the central police station in Tokyo, who has learnt to give Toshio whatever he wants, and puts up with being called 'Uncle P' (for 'police') by him in exchange for his invaluable help.
The two Edogawa Rampo juvenile detective stories that I've read avoid actual bloodshed. Kosakai is not so restrained. The first two stories are thefts; but every story after that features a murder. The concession to young readers is that they are all a bit easy. I imagine most children and any adult familiar with detective stories will see who did it in every case. That doesn't mean they have no interest as detective stories. The culprit may not come as a surprise, but there are often excellent clues and elements to the puzzle that the reader may not have spotted.
The best stories, I think, are 'The Scarlet Diamond', 'The Riddle of the Beard' and 'The Secret of the Skull'. 'The Scarlet Diamond' introduces the characters and has an interesting code-breaking puzzle. Obviously this works better if you're reading in Japanese; but I hope I've done enough to let a western reader get something from it too. 'The Riddle of the Beard' is a complex and fairly clued murder mystery. 'The Secret of the Skull' is a dramatic story of forensic reconstruction, as Toshio applies the western technique of putting clay on a skull to find the face of the victim. It too is well clued. Of the others, 'A Fight in the Dark' is a lively story of the capture of a gang of thieves. The mystery element is weak, but the science part is kept up. 'Ultraviolet Rays' is the most complex mystery in the collection; but as there are few clues, most of this is revealed by the criminal's confession at the end. 'The Wisdom of a Fool' seems to me the weakest in the collection, with no clues but an obvious villain, and no real scientific element.
Beyond their interest as mysteries, the stories also have some interest as a view of Tokyo and the surrounding countryside in the early twenties.