The days and the months are drifting by
As though they didn't notice seasons changing in the breeze
They all look the same but I sense something's there
Waiting around the path
Revealing a truth that I will defend
"Time Hollow" (Mouse)
Despite the cover, this is technically a science-fiction mystery, I guess...
The Shiigahara Academy Case some years ago involved the death of a female science teacher of that school, for which the prosecutor Meijou was arrested. He insisted he was innocent, but evidence showed that only he came near the victim after she herself signed for a certain delivery at the school, namely a package containing the very poison that would be used for her death. Meijou was convicted for the murder, though some suspect the fact Meijou was working on a grand scale corruption case involving the Shiigahara Group (which funded the academy) might not be completely unrelated to his predicament. Some time later, prosecutor Kikuzono Ayako receives a tip from attorney Morie Shunsaku that might allow them to prove Meijou's innocence, as the research center HICALI has a particle accelerator that can determine at the particle level whether a certain piece of evidence used in Meijou's trial is indeed what it was assumed to be. After leaving the evidence behind at HICALI, Kikuzono is taken by Morie to the Everholy Lodge, a private hotel owned by the Shiigahara Group for its members. There they find among the other guests some people that might be connected to Meijou's case too, but to the two attorneys' surprise, one of the guests is murdered inside a locked hotel room. Kikuzono however quickly figures out who committed the murder and how... or did she? For at the very moment she pointed out who the murderer was, she is transported to another dimension! It appears a fault with HICALI's particle accelerator is the cause of her dimension-hopping, and she theorizes that she might be flung back into her own world if she manages to solve the murder in the Everholy Lodge, but there is one problem: while this parallel world is mostly like her own world, it appears that the vital clue in Kikuzono's original theory doesn't exists in this parallel world, meaning she has to figure out a whole new explanation for the locked room murder in Ashibe Taku's Ijigen no Yakata no Satsujin ("The Murder In The Dimensional House", 2014).
This is a weird novel. Mystery fiction is not necessarily about realism of course, and the rate at which most amateur detectives run into corpses or other mysteries like impossible disappearances is hardly something anyone would consider realistic. World consistency is more important and this is why fantasy and science-fiction mystery novels work: they might not be "realistic", but ideally, there's consistency in what can be done or what can't be done with magic/future technology, and those rules govern those worlds just in the way the general laws of nature govern most other mystery stories. Yet Ijigen no Yakata no Satsujin seems quite strange compared to other novels in the Morie Shunsaku series: sure, this series is strangely broad, as in one novel, Morie might be acting like a real attorney, working on a Lay Judge case that is meant to portray how a Lay Judge case really works in Japan, but in another story he might be solving the mystery of a Birdman or solving purely fictional murders. Yet I had not expected him to appear in a science-fiction mystery, which this novel is essentially, as we're talking about a dimension-leaping prosecutor. That said though, the parallel world premise is the only science-fiction part of the mystery, as it's not like the murder was committed with death rays or anything like that. The story follows prosecutor Kikuzono by the way, who is apparently a semi-recurring character/rival in the series I myself hadn't met yet, rather than Morie himself.
The premise is that due to an incident at HICALI's particle accelerator, Kikuzono is flung into a parallel world each time she makes a wrong deduction. She realizes she can only return if she figure out who the real murderer is of the Everholy Lodge Murder Case, but the catch is that every parallel world is slightly different. The murder has happened in each world, but everyone has slightly different names for example (in one of the worlds, Morie has an expy called Emori for example) and the details of the murder are also slightly different. The devil is in the details they say and that is correct here, as it's these details that make each dimensional jump so tiresome for Kikuzono, as each time, her previous theory about the murder is rendered completely useless. For example, in one parallel world, her theory hinged on the fact the murder weapon was a fairly small knife, but the moment she pointed at her suspect, she was thrown into another parallel world, where the knife had turned into a Japanese sword, that couldn't possibly work with her theory. Each time the details of the case change slightly, making her previous theory impossible and forcing her to rethink it.
This idea is somewhat similar to the multiple solutions trope we see in stories by Ellery Queen (most famously The Greek Coffin Mystery) and Anthony Berkeley (most famously The Poisoned Chocolates Case), novels which are structured around presenting one new solution to the same case upon another to the reader. There is a fundamental difference however to the parallel worlds in Ijigen no Yakata no Satsujin and those works: in the works of Queen or Berkeley, the false solution is possible because a detective either interprets the evidence wrong, or more often, they are not yet in possession of all the relevant facts. It's only after the false solution is proposed that New Evidence A appears on the scene, which allows the detective to refine their theory to include this New Evidence A, changing their solution (see also my article on the Foil Detective). This is not the case in Ijigen no Yakata no Satsujin: in this novel, the facts themselves actually change or even completely disappear, forcing Kikuzono to reconsider her theories. So what was once a knife, can suddenly turn into a sword, or an item that existed in one world that allowed her theory to work, doesn't even exist in the next parallel world. So in this novel, the false solution is not made possible by adding facts, but by removing them or altering them. This wouldn't fly in a "realistic" novel of course, but does work in the framework of parallel worlds.
Ijigen no Yakata no Satsujin is thus more a thought experiment in deduction and the locked room mystery, than a mystery novel that wants to challenge you in a fair way with false solutions, as it's obviously not fair to the reader, nor to Kikuzono, that fundamental facts are suddenly changed at the whim of the author/parallel worlds. It's a mostly entertaining experiment though, as Kikuzono has to come up with a new solution to the locked room murder each time with a diminishing number of clues, and I think she goes through like four or five different solutions on what is essentially a rather small-scale locked room mystery, but which eventually makes an impression because of all the variations it goes through. But there's quite some repetition in this novel due to all the dimensional hopping, and because the facts keep changing solely to deny Kikuzono's theories, it feels somewhat mean-spirited, and at times even futile, as her theories are always rejected not because they are logically not sound, but simply because the facts are changed to her disadvantage.
The final solution to the locked room murder... is almost too grand for this novel. The solution takes some minor elements from each of the other solutions Kikuzono proposed in the parallel dimensions, which makes this a pretty clever one, but even from that starting point it's a looooong way to the final solution, and it definitely needed better clewing, as it really came out of nowhere, even with the build-up through the other solutions. It's a shame, as the core concept of this locked room mystery is utterly nuts, in the good sense of the term, but the minimalist clewing doesn't do it any favors, as at it is now, it's only vaguely hinted at best, and even then there's so many logistics about it that could've been hinted at in a better manner. The idea is of course that each of the previous parallel world solutions all contain elements of the final solution, but even then, I think that this final solution to the locked room mystery would've worked better on its own, with it as the true focus, rather in this particular novel that's more built around the idea of having multiple parallel versions of the same locked room.
What struck me the most I think was the nagging feeling that this story would've worked better as a videogame, as that medium works better with presenting parallel worlds. Kamaitaichi no Yoru, 428 or Rei-Jin-G-Lu-P also work with branching and/or parallel story paths and as games, they can allow the player to do stuff easily like jumping back and forth between different paths through flowcharts. I think Ijigen no Yakata no Satsujin would've been more fun if the parallel worlds weren't presented one after another, but simultaneously (allowing you to jump between the various worlds), allowing you to explore each world yourself, rather than going through them in order.
I said it at the beginning and I will repeat it now: Ijigen no Yakata no Satsujin is a weird story. It uses a science-fiction framework to play with the trope of the false solution in an interesting way, focusing on a somewhat simple locked room mystery and it's quite entertaining to read it as such. Yet I also feel that this concept might've worked better in a different format, and that the true solution of the locked room mystery is crazy enough that it deserved more attention as a full-fledged novel that is solely about it, rather than being part of a number of solutions to the locked room conundrum, as the clewing for the true solution is somewhat inadequate. It's definitely not a typical Morie Shunsaku novel, though I have to say: by now it seems that Morie Shunsaku can work with any type of mystery.
Original Japanese title(s): 芦辺拓 『異次元の館の殺人』