Diamonds Are a Ghoul's Best Friend

"Curious, how everyone who touches those diamonds seems to... die."

"Diamonds are Forever"

Kaiki Tantei Sharaku Homura ("Sharaku Homura: Detective of the Uncanny") was easily one of my most surprising reads two years ago. This doujin comic (self-published comic) by professional comic artist Nemoto Shou (who uses the doujin circle name Sapporo no Rokujou Hitoma) was an excellent mystery comic focusing on impossible crimes and a great example of how to do fair-play visual mystery fiction in general. Heck, the stories even feature formal Challenges to the Reader! Nemoto has been doing annual releases for about a decade now, but like most doujin comics, they can be tricky to find if you're not located in Japan because self-published materials are usually sold at events like conventions or through mail order. The last few years, we have also seen doujin circles selling their products digitally themselves, but Kaiki Tantei Sharaku Homura went a completely different direction: major publisher Bungeishunju decided to put this fantastic comic on digital storefronts in Japan, compiling the first fourteen issues into three volumes (reviews of the first, second and third volume here). Last year, I also reviewed the wonderful sixteenth issue: Hagoromo no Kijo ("The Ogress With the Robe of Feathers") was another great entry in the series about an impossible stabbing in a snow-covered field without any footprints of the murderer, and the solution was highly original yet very well set-up.

Our detective duo from Shimoyama Middle School returns in the eighteenth issue of Kaiki Tantei Sharaku Homura titled Kourei Yashiki ("The House of Necromancy" 2020), a story submitted to the Hokkaido Mystery Cross Match Award competition and which can be read here. The clever girl detective Sharaku Homura and her assistant Yamazaki "Karate Kid" Yousuke are out in the mountains looking for materials to use in science experiments when they are surprised by the rain. Looking for shelter, they stumble upon a old, decrepit old inn which is now the property of the spirit medium Maruyama Kamazu. They meet the high school student Akagawa Hasuko there, who explains to the duo that she and her father are here for a seance, because her father wants to speak with her mother again, who died recently. She also confides to them that she suspects her father is more interested in learning where her mother left her secret savings. Hasuko arranges so Homura and Karate Kid can stay in the house until the rain stops and inside they meet the creepy spirit medium Kamazu, Hasuko's father and two acquaintances of the family: the surgeon who owns the hospital where Hasuko's mother was treated and a jewelry dealer with whom Hasuko's mother often did business. Hasuko explains she also brought her mother's beloved taaffeite with her, as the valuable gem will be used as a medium to channel her mother's spirit.

Late at night, everyone in the house is summoned to the annex for the seance session. The annex is a small building with only one entrance and one barred window, while the upper attic floor can't be reached because the ladder has been removed.  The gem is set in the middle of the table, with everyone seated around it. To make sure there are no shenigans going on, everybody is chained to the legs of their chairs and they have to put on handcuffs too. Even the medium Kamazu undergoes the same treatment, placing the key in front of him on the table. At first, the seance seems to be going well, but then the lights in the building suddenly go out for a second, and the next moment, they discover the gem has disappeared from the table! Any one of them may have reached out to the middle of the table to grab the gem, but because they are all still tied to their chairs, Homura orders everyone to stay put as she calls the police, figuring the thief must still be carrying the gem. But when the police arrive, they learn that nobody is hiding the gem on their person, and a search of the empty annex doesn't lead to any results either, meaning the gem has somehow disappeared completely. Given that no person could've stolen the gem, does that mean the ghost of the dead wife took the gem with her to the other side?

Stories that don't focus on an impossible murder are in the minority in this series, but we still have an impossible disappearance here. The problem is fairly simple: where did the gem disappear to? Given that the annex is very small, with the only entrance locked from the inside, a barred window preventing the thief to throw the gem far away outside and everyone having been tied up to their chairs during the seance, it doesn't seem the thief could've done much with the gem, and yet the police can't find it. Homura of course does figure out where the gem is, and I think it's here where Nemoto really shows off his gift for plotting a mystery story. Just taken on its own, the hiding place of the gem is quite clever, if somewhat simple. But it's what Nemoto does on top of this idea that makes Kourei Yashiki a better story than it could have been. For the story doesn't only revolve around the disappearance of the gem, the author also made sure it's actually possible for the reader to deduce on their own what happend to the gem, and who did it, based on clever visual clues. Many authors would've just called it a day with only the disappearance trick, but Nemoto also prepared two distinct lines of reasoning for the reader to pick up: one that gives a valuable hint as to the whereabouts of the gem, and one line that points to the identity of the thief. It's because of these clues that the Challenge to the Reader actually feels fair: Nemoto made sure you didn't have to *miraculously* think of the hiding spot, but expects the reader to deduce where the gem is hidden and by whom based on the clues he left.

The clues that point to the hiding spot of the gem are really good too. It makes brilliant use of the visual medium of Kaiki Tantei Sharaku Homura: the clue is set-up across several scenes throughout the story, but it's very easy to miss, yet one can't even claim it was too obscure, as the story does really place a lot of attention to this part at one point, but it is likely the reader will overlook the importance of that scene, which is exactly what you want from mystery fiction. It's a clue that could also work in normal prose fiction, but I think I would find it not as fair there, as the visual medium really adds a lot, without making it too obvious. The other line of reasoning that points to the identity of the thief is also in essence simple, but it too feels really fair, yet subtle thanks to the visual medium: it sorta feels like it makes use of comic grammar and the shortcuts used there to fool the reader, but the attentive reader should feel something's up here. The story ends with some other minor mysteries that Homura manages to solve too, though part of that is already revealed beforehand to the reader and only kept hidden from the characters in the story, so the reader has the advantage over her there (though one could argue that that knowledge could function as a red herring for the impossible disappearance).

By the way, there are of course more stories about crimes/mysteries that occur during a seance like Lovesey's A Case of Spirits but personally, one of the early cases from Tantei Gakuen Q is always the first one I think of when it comes to seance mysteries. They do make for interesting impossible crime situations, as people are often required to hold hands etc. during a seance, making it seemingly impossible for one single person to act without others noticing.

Kourei Yashiki, the eighteenth issue of Kaiki Tantei Sharaku Homura, may not revolve around murder this time, but it's still a very enjoyable entry in the series. It might lack the surprise factor of Hagoromo no Kijo ("The Ogress With the Robe of Feathers"), but this is definitely a very well-written mystery story, that shows that even with ostensibly simple elements, you can come up with a satisfying mystery story through good plotting. And with four uncollected issues out now, I do think it's about time for that fourth volume...

Original Japanese title(s): 根本尚（札幌の六畳一間）「怪奇探偵　降霊屋敷」