"Playful" isn't a word you usually connect to murder mysteries, except maybe in a sadistic, Jigsaw-kinda way, but for this book, I really mean it. Soji Shimada pops in twice to tell you to sit down and solve the mystery before you go on, and the solution is so clever and out there that you might never get it!
The Tokyo Zodiac Murders is a classic Japanese murder mystery from 1981. I read it in grad school maybe 15 years ago, and it's been hard to get a copy affordably until recently, since the book had such limited printings in English. Fortunately, a recent printing makes this book accessible at a relatively low price, which was just the opportunity I was waiting for.