While the title of today's book sounds weird without the context, it works excellent as a memorable catchphrase in this book!
Fifteen years ago, when Rize was only six or seven, her mother joined the cult Apolutrosis, a doomsday cult that combined both Christian and Shinto concepts. The two moved to the small community of the leader of Apolutrosis and his followers, a village with exactly thirty-three inhabitants located in a kind of valley, surrounded by high cliffs and only accessible through a tunnel through said cliffs. The people of the cult had mostly distanced themselves from the outside world, their livelihood dependent on the simple farm they had, the waterfall and river that crossed their village and the occasional trade with nearby villages. Life was tough of course, but not horrible, and Rize also had one friend in the village: Douni, a teenage boy, and the two were the only children in the village and dreamed of escaping together one day. One fateful day, an earthquake stopped the waterfall's run, resulting in a dried-up river. The cult leader saw this as a sign of upcoming doom, and after blowing up the tunnel (the only exit out of the village) with explosives and a long ceremony, he called his followers to the house of prayer. The followers were to close their eyes and pray, but when Rize took a peek, she witnessed a horrible sight: the leader was chopping everybody's head off with an axe! Rize, who had injured her leg during the earthquake, was quickly carried away by Douni, who locked the house of prayer from the outside. Rize passed out during the escape, but when she came by, she was confronted with something even more horrifying: the chopped-of head of Douni, lying next to his body! Rize was lying in the shrine in a cave near the waterfall, but she has no idea what had happened to her and Douni after she fainted. It took more than a week after the horrible mass suicide for help from outside to arrive, but when the authorities investigated the case, they realized this was no ordinary case.
A book with an amazing premise: Ueoro desperately wants to find a genuine miracle, an event that can not be explained according to human knowledge and his method thus involves considering each possible solution and prove that they are wrong. Interestingly, this happens very quickly and off-screen: the next time we see Ueoro after he is hired by Rize, he has already compiled a bookwork that explains how every possible explanation can be ruled out, and that therefore her experience is a true miracle. It's at this point that Ueoro and Fulin are visited by some familiar faces from their pasts, who seem intent on showing that Ueoro is in fact wrong, and that there are still possibilities left unexplored by Ueoro. Each of these visitors come up with outrageous theories that make the events in the village seemingly and theoretically possible and it's up to Ueoro (and occasionally Fulin) to prove that even those possibilities are actually impossible.
The result is a story that is truly unlike any other mystery novel, because the goal of this book is not to arrive at the single truth at the end of the book, but deny all possible solutions. This results in a very different approach to the detective story. The various solutions proposed by the visitors for example are never meant to be theories that actually explain what happened in the village, and everyone is aware of that. Some of them paint Rize as the murderer of course, even though the proposers themselves don't actually believe she did it. But as long as the possibility that the theory can be correct exists, Ueoro has to find a way to refute them. While the theories proposed have to be based on the known facts, that still allows a lot of room for theories that might sound a bit far-fetched, but which are undeniably possible. The theories are very entertaining, each focusing on a different aspect of the mystery (for example: a brilliant idea to show how the blade could have been moved) and they very cleverly use everything presented in the introduction to weave a completely plausible possibility of how everyone besides Rize ended up dead. Each of these solutions would've worked perfectly as a memorable solution on their own (the first one is amazing) and it's absolutely baffling how author Inoue managed to come up with three radically different, and surprising solutions based on the same basic setting. Equally impressive is the fact that Ueoro uses the same facts to not just prove that these theories are not what happened, he proves that they're simply impossible, denying the possibility of them entirely. Little facts here and there are put together that make it clear that the premise of each of those theories doesn't work, but it's always only after Ueoro points those facts out that you realize those theories wouldn't have worked in the first place and that the evidence had been staring at you all the time.
Your mileage may vary on the characters that appear though. It has a bit of a hardboiled action film vibe, with Fulin as some kind of expert on Chinese torture methods, and people from the underworld popping up here and there to challenge Ueoro and Fulin in deduction battles and what not. The book plays this pretty seriously, which in turn made it for me very hard to take it seriously, because it was just so weird and I never did really get attached to the characters, but perhaps another reader might like them better.
The last third of the novel starts off with a surprising and very memorable point made about Ueoro's methods which seem to nullify everything he has done until that point, but afterwards the discussion becomes more a meta-discussion and the focus shifts away from the actual mystery of the village, so it depends on the reader whether you'll like this part. If you like discussions on the Proof of the Devil like in Umineko no Naku Koro ni, you might like this last part of the book better than I did, because it's a bit like the discussions in those games in spirit, but like the book itself later points out, ultimately it's not that big of a deal. The ending of the book was also a bit disappointing: considering the set-up of the book, it was quite likely this would be the way the story would eventually wrap up, but it does make a lot of the story feel rather futile, despite the earlier battles of the wits being quite amusing.
Because of its unique angle, Sono Kanousei wa Sude ni Kangaeta might not be the kind of detective story that'll appeal to everyone: the plot will meander a lot, and because the goal of the story is to not arrive at the solution, a lot of what happens will just seem useless in hindsight. If you like Ellery Queen-style mysteries and the long chains of deductions that occur there though, this is a great book! It has battles of the wits, impressively built lines of reasoning built on brilliant interpretations of the known facts and evidence and likewise memorable and meticulously built-up rebukes of those theories. The book might get a bit philosophical near the end, but still, a fantastic read for those who're into this stuff.
