Despite these Japanese locked room mysteries supposedly being all about the mystery and the clues peppered throughout (a reader should be able to figure it out with the clues provided), with character and psychology being secondary, I noticed the this book and The Tokyo Zodiac Murders have similar characters. The lead ‘detective,’ in the case of Decagon, a man named Shimada, is a whimsical, almost romantic amateur (I need hardly add that I don’t mean ‘romantic’ in anything resembling an erotic sense).

This book ran in two tracks: on the mainland, where some amateur detectives get an idea of a potential mystery; and one an island (with the titular house) where you sort of know that everyone is going to die. While a neat idea, it also didn’t quite work for me. The island scenes were overly dramatic, but in retrospect, only existed to give us the clues we would need, as readers.

Now, I will freely admit that I didn’t figure out the mystery until the author revealed it. And even though I was disappointed, I won’t be afraid to try another Japanese mystery novel.