Premise: A reporter found a powerful A.I. (from the future) in a hourglass form and he is going to use the power of this 'magical hourglass' to go back in time in order to save his dying wife before the family curse which the wife and her family have been suffering with kills her!
Said family's curse caused a mass murder from 40+ years ago with 10+ people getting killed, if the reporter wants to break the curse, he must go back in time to solve this 'Locked Room Mystery + Impossible Crime' level of mass murder, how will this adventure go?
The Time Traveler's Hourglass is a delightful mixture of Sci-Fi and crime & mystery story, despite its many characters the story is still neat and easy to understand. Plus the few main characters are well written enough, as well.
Although which is a bit nontraditional, but overall I'm pleased with this novel and how the murder mystery is explained! Will keep an eye on more of this novelist's works!
The Time Traveler's Hourglass is extremely convoluted and densely-plotted but completely fair all throughout. Our main man Kamo Touma goes back 60 years into the past to prevent a multi-murder familial tragedy that provides the source of a curse that threatens the death of his wife in 2018, and as the last descendant, her entire bloodline. A veritable entry into the hybrid-mystery subcategory of shin-honkaku, it features all the traditional aspects of Golden Age Japanese mysteries (intricate corpse puzzles, deceptive alibi tricks, Queenian culprit deduction) while mixing in the realm of Sci-fi with time travel. Where Hourglass becomes such a breath of fresh air is the establishment of clear rules for its usage. Similar to how Imamura's Death Among the Undead (which I am told is the best of this genre), outlines clear barriers as to how zombies can operate, limiting their involvement in the many impossible crimes, Hourglass doesn't skimp on the technical aspects of how a time-traveling hourglass works to make sure readers have all the information necessary to work within its boundaries. One can't simply assume everything was committed using time travel, and in fact, in certain cases, it proves as much a red herring as a legitimately central tool to solving the mystery.
What makes Hourglass so unique in this respect though, is that Houjou has that secret sauce for clewing. Unlike some hybrids that go out of their way to add new constraints for complexity's sake, I can't think of a single thing or rule in this book mentioned that didn't get resolved or at the very least addressed later on. It plays proper and is thus extremely satisfying to read through, and though I came nowhere close to solving it, I feel I've been hoodwinked by the author in the fairest way possible.
Hourglass also contains a lot of heartwarming moments. You feel bad for many of the folks in the novel as they undergo this closed-circle situation, and unlike Kamosaki's Golden Age of Locked Room Trilogy, Hourglass doesn't feel the need to sacrifice characterization for a tighter puzzle. (Although it did get a tad bit contrived toward the end with all the hidden relationships.)
In tbe end, Hourglass ends up being a unique and refreshing take on a mystery, a harbinger of sorts of the many possibilities the genre is replete with that gives me hope for posterity. Quite possibly one of the most perfect mysteries I've ever read.