I loooove the cover art of this book! Apparently, the book had an exclusive early partial release on digital storefronts, with the first half of the book being offered completely free, and those digital releases had exclusive cover art too with characters (one of them featured below in the review).
Kouzushima Tarou became a hero in the medical world with his invention of a revolutionary drug delivery system called Trident, and the patent also made him wealthy enough to indulge in his true passion: mystery fiction. Mostly retired now, Kouzushima lives with his servants in the mountains of Nagano Prefecture, in a curious building that seems to come straight out of one of those detective novels Kouzushima loves so much. The high cone-shaped tower stands high on the mountain and has glass exterior walls, with each floor above the ground floor having only one single room and a big spiral staircase at the centre of the building. This is where Kouzushima also keeps his valuable mystery collection, which includes rare editions and props from series like Columbo, but also more recent productions like Sherlock and Knives Out. Having something important to announce, the eccentric recluse has invited a few guests to stay in the glass tower. While the precise contents of his announcements are not known, the fact the list of guests include people like the Nagano police detective Kagami, veteran mystery writer Kuruma Koushin, Sakyou Kousuke, editor at one of the most prominent mystery publishers, the spirit medium Yumeyomi Suishou and the great detective Aoi Tsukiyo ("great" is part of her title) is enough to tip off everyone that Kouzushima's announcement is related to his beloved fictional genre. Another name on the list is Ichijou Yuuma, Kouzushima's young physician, who however has a different reason to be here: he's here to kill his boss. In order to save a loved one, Ichijou has no other option left anymore but to kill Kouzushima, but of course in a way that will arouse no suspicion. This little party is the perfect occassion: the plan is to make Kouzushima take some poison and then create a locked room of the study. When Kouzushima doesn't appear for his announcement, they'll go up to Kouzushima's floor, break into the locked study and then Ichijou will declare the man died of a heart attack, and he'll live happily ever after.
While Kagami acts like the Stereotypical Police Detective in Mystery Fiction by wanting to keep Tsukiyo and everyone else out and insists on waiting for the proper authorities to arrive, Tsukiyo and Ichijou work together and try to figure out who committed the murders. Well, to be exact, Ichijou is helping Tsukiyo to find out who the other murderer is, while also trying to conceal his own involvement in the first murder. This of course easier said than done, especially as the second murderer keeps on killing people and always in locked rooms. Even measures like keeping the master key in a safe and having two different people keeping the two keys necessary to open it doesn't seem to faze the other murderer. What Tsukiyo, Ichijou and the others can do however, is theorize about the murders and they do this in the context of shin honkaku mystery novels. No work is outright spoiled of course, but they do discuss common tropes, concepts and themes seen in shin honkaku novels and see how they could apply to their current situation. Chinen obviously designed all the murders in this novel to invoke common ideas seen in shin honkaku mystery fiction, especially early shin honkaku novels with grand, over-the-top tricks that are utterly fantastical but oh-so entertaining, and thus the book provides a great vehicle to look back at how themes developed early on in the shin honkaku movement and challenge the reader to guess how these ideas apply to the murders in this book.
The (intended) result is that at times, Garasu no Tou no Satsujin will feel a bit familiar: while it doesn't 'steal' solutions from other novels, the concepts and twists will often remind of other books, but that is an inevitable result of the focus of this book, as it wants to use this to fanboy over the classic shin honkaku novels. Personally, I think people who are fairly familiar with the history of shin honkaku will find a lot more to enjoy about this novel, as a lot of the key points of this novel are written especially to appeal to those people. As a "conventional" mystery novel, there are just too many references to real-life history of shin honkaku and meta-discussions about it, and you'll probably feel like you're missing a lot of the story without that context (which is true). That said, the various locked room murders are, in concept, quite enjoyable, with ideas that make good use of the unique setting.
The secondary whodunnit plot also adds a lot of great tension: we know that the narrator Ichijou's the murderer of Kouzushima, but there's also the presence of the second murderer, who manages to pull off impossible murders in the glass tower despite the presence of the great detective Tsukiyo, and you have the added suspense of Ichijou actually being Tsukiyo's Watson, hoping to find the second murderer first so he can frame them for the first murder too. This plot-thread of Ichijou being both the murderer and detective('s assistant) adds a lot of twist and turns making Garasu no Tou no Satsujin a much more tricky and complex reading experience than the first chapter might make you think it will be. The book kinda spoils itself by the way in that regard, as at one point, the story kinda works towards a conclusion.... but you'll still have about twenty percent of the book left unread, so you know even more twists and turns are coming up. That's one advantage mystery games have over books!
Garasu no Tou no Satsujin is a very densily packed novel, featuring a lot of familiar tropes and concepts of the genre, but that's intentional and it's actually used in a very meaningful manner to present what is basically a love letter to the shin honkaku sub-genre. It presents a romantic view back at the familiar tropes from shin honkaku novels, while also telling a capable mystery itself too, though still firmly set in the context of those novels. This means that you'll be able to get a lot more out of this novel if you're familiar with the novels and authors in question and that the book is probably less fun if you lack that context, because some of the trickery utilized and the character motivations might seem a bit weird in that case, but personally, I found this to be a very entertaining puzzler that presented a surprising deep look at the genre.
