Left with only the memories is too painful, the impossible window won''t open
There is only one key and you keep it until eternity
"Only the memories are too painful" (Shibasaki Kou)
Now I think about it, a detective story based on memories is pretty cool, but it wouldn't work with me and my awful memory. Sometimes, a miracle happens where I remember things from some years ago (like mentioned here), but usually, I am pretty good at forgetting names / faces / persons / events.
But anyway, have you ever looked back at something that happened to you, or maybe just an incident you saw or heard about, and only realized the full meaning of that event at a later point? Maybe you saw someone strange one day, and only much later realized he must have been the one who robbed the bank around the corner. In a sense, the potential of a perfect detective lies within all of us, and that is the premise of Nishizawa Yasuhiko's Kanzen Muketsu no Meitantei ("A Perfect Detective"). Protagonist Yamabuki Miharu is not a detective. But he has the ability to make everyone into a detective. Miharu has the power to make people talk about little things that bug them, even though he himself, and his conversation partners don't realize that. And as people start to talk about anecdotes, about events they saw years ago, things they heard in other parts of the country, they slowly, but surely start to see the circumstances they had recorded in their memory from different angles. The wealthy Shirakage Gen'emon sends Miharu to the Kouchi prefecture, where his grandaughter is working at an university against his wishes. Something is keeping Rin in Kouchi and Gen'emon hopes that Miharu's powers will help Rin discover what that is.
I have read very little by Nishizawa Yasuhiko and written even less about him on this blog (for such evil reasons as forgetting to make proper notes of a book I had borrowed). His novels often feature supernatural powers, but used in a completely fair way (heck, I once read a book by him where people had psychokinetic powers, and it was still a completely fair and logic locked room mystery!).
So Miharu's powers shouldn't scare off people interested in a good mystery as it is not used as an unfair device.
Kanzen Muketsu no Meitantei is best described as a connected short story collection (even though it's technically a novel). While the problem of Rin is the main propellant of the plot, most of the book is actually episodically structured: usually Miharu would meet a random person, have a deep talk with him/her, and his conversation partner would eventually realize a shocking truth lies behind something he/she experienced in the past. The episodes are short mystery stories of the intuistic school: as the conversation partners tell their tales, they slowly notice some inconsistencies in their recollections. These eventually lead to new revelations. While these stories rarely feature hard evidence (and also note that everything is based on memory), the deductions these people make never seem too farfetched and it is quite amusing to see how based on memories of small inconsistencies, people can come up with the most outrageous ideas. Somewhat like a single-man Columbo show, where you think of a 'wrong' crime scene and solve the crime yourself all in your head!
Personally though, I had preferred for Nishizawa to have used this device in an everyday life mystery style. The style of stories based on recollections, on vague memories and resulting deductions seems to me better fitting for the everyday life mystery. In Kanzen Muketsu no Meitantei however, every person who speaks with Miharu seems to have been connected to some crime one way or another (though usually unconciously). What's even more ridiculous is that everybody is eventually connected to the main story. Miharu's let-them-talk power is nothing compared to the mysterious power to only meet important persons over the course of the novel, and extract crucial information related to Rin and the main plot all under the guise of coincidence.
It really thought the mode of deduction in this novel was more suited for everyday life mysteries, so I found the overall plot to be surprisingly dark. If I think about it calmly, Kanzen Mukatsu no Meitantei is not particular much darker than most mystery novels I read, but the method of going into memories and stuff fits stories with just a 'hahaha, so it was that!'-type of plot better in my opinion, rather than 'oh... that was pretty evil and dark and no wonder you were killed'-type of plot (with this novel eventually being the latter). That said, the overall plot is actually well structured, with some cool tricks played on everyone through the device of Miharu's powers. I might have prefered a different approach, but Nishizawa should never be underestimated when it comes to mystery stories.
Kanzen Mukatsu no Meitantei is not a bad story by any standard, and the idea of having every other character but the protagonist eventually turn out to be the detectives of their own stories is really good. I thought the basic premise of the book and the actual plot didn't mesh really well, but your mileage may well vary on that. But too be perfectly honest, I thought that Nishizawa Yasuhiko's Nendou Misshitsu ("Psychokinetic Locked Room!") was better overall, also as an entry point into his novels.
Original Japanese title(s): 西澤保彦 『完全無欠な名探偵』