This is a good story, but the translation leaves a lot to be desired. The translator seems to have decided that if he or she used a lot of American colloquialisms, it would sound like native English. But the excessive use of colloquialisms in this book just makes it sound kind of like a clunky translation.
At any rate, if you can get past the translation, the story itself is pretty compelling and the details of the mystery are good. I had figured out the answer, though, by the time I was halfway through the book.