In Ayatsuji’s The Decagon House Murders, seven mystery writers are trapped on a Japanese island with a fiendishly clever killer.
What appeals to you about puzzle mysteries?
At 11, I first read Ellery Queen’s early novels, and I was amazed by the quality of the logical structure of those novels. What appeals to me is the shock of the unexpected conclusion. Note that the ending shouldn’t just be shocking: the surprise twist should only be done within the framework of a logically structured plot, with hints pointing to the twist, planted across the story from the start. Imagine looking at a negative of a picture, which at the end of the tale turns into a beautiful positive image. The world as you knew it suddenly changes dramatically. A good puzzle mystery is one that gives us such a colorful shock.
Your book features members of the Kyoto University Mystery Club; is there really such a group?
The Kyoto University Mystery Club was formed by students with an interest in mystery fiction, and it has been around for 40 years. Writing has always been a major activity of the club, but I was the first member of the club to become a professional writer. After my debut, more members became professional mystery writers, too, so the club is now considered a sort of prestigious club in Japan. I entered the club in 1979, and there was of course nothing like the Internet back then. So becoming a member of a club where people with similar interests gathered and with whom you could share information and thoughts was very important.
Where did the plot for Decagon come from?
I am a big fan of Agatha Christie’s And Then There Were None, so I had the idea of doing an homage. A group of young people gathered on an island, killed one by one by an unknown murderer, with no way to escape from the island, no way to contact the police. This setting is incredibly suspenseful and appealing. So I had this setting, but I also needed to come up with a surprising truth of my own. Thinking about what that could be was my starting point.
How do you go about planting fair clues?
The rule I have laid out for myself when writing is to never present false information in the third-person narration. That’s the very least I need to do to ensure the mystery plot is fair toward the readers. From there, I add lines at the key parts of the story intended to mislead the readers, lines that usually have double meanings. If you change your way of looking at them, the misdirection changes into a hint pointing toward the solution.