In The Aosawa Murders (Bitter Lemon, Feb.), Onda gradually unveils the truth behind a mass murder.

Where did the idea for the book come from?

I have been a big fan of Michel Petrucciani ever since student days, and always captivated in particular by his song “Eugenia.” It inspired me to write a poem. Then, some years later, when I was thinking about what kind of story the poem could be part of, I decided it had to be a complicated intrigue of life and death, and probably set in a town by the sea somewhere in the Hokuriku region, where I had lived as a child.

What did having the story unfold as answers to an unseen interviewer’s questions allow you to do that you couldn’t have otherwise?

I was attempting to write a novel that gradually made the reader feel more and more uncertain, and responding to an unseen interviewer was effective for drawing out that feeling of unease, I believe. I wanted to write about a gray zone that can’t be expressed in a dualistic discourse of good or evil, friend or foe, and thought that this technique would make readers feel the sense of ambiguity and lack of definitiveness.

Many readers will associate the format, with different characters giving different perspectives and memories of the events surrounding the murders, with the film Rashomon. Was that an influence?

“In a thicket” is the phrase used in Japan for a Rashomon-type situation, meaning that something is hidden or mysterious. I like this kind of story very much, so I’m sure I was conscious of it at some level.

Why did you quit your job to try writing a novel?

The usual route to becoming a novelist in Japan is to enter competitions. I had wanted to be a writer since I was a child, but I also had an image of a writer as someone with experience in society, who has studied writing, and reached a certain age. However, when Ken’ichi Sakemi, who was only a year older than me, made his debut at 25 with a fascinating and highly accomplished novel, I realized it was okay for me to start, too.

Is it harder to write a mystery than a nongenre novel, such as your recent book about a piano competition?

Different genres necessitate using different parts of the brain, so it’s not a question of one being easier than another. All are hard work. Writing mysteries requires coming up with an engaging puzzle and constructing the process for solving that puzzle with narrative consistency. Logical thinking is my weak point though, so perhaps the genre is a difficult one for me.