It's not as bad as how it went with Kubinashiyakata no Satsujin, but still, I wrote this review 12 months + a week after reading the book. And then the review still had to wait a few months for publication! In the time between me writing this post and it getting published, they actually announced a live-action drama is in production, which will start airing in July and it's directed by none other than Tsutsumi, the director of the original Kindaichi Shounen no Jikenbo drama series, Keizoku and of course Trick!
Knockin' On Locked Door is the title of a 2016 short story collection by Aosaki Yuugo, the name of the title story in said collection and the name of the detective agency run by Gotemba Touri and Katanashi Hisame, though their part-time assistant/housekeeper Kusuriko will probably argue she's actually one trying to get the agency to be succesful. While both Touri and Hisame can be a bit eccentric in their own ways, the unique part of their agency is that the two detectives are very specialized and that they are in a way equal co-workers, but also minor rivals. For Touri specializes in impossible crimes (howdunnit), while Hisame focuses on inexplicable crimes (whydunnit). Each time a new client arrives at the agency, both detectives of course hope they'll be the one to handle the crime, as the other is usually just forced to play assistant for the other and thus have the most boring day ever, though on lucky days, they come across cases that require the abilities of both these detectives. Occasionally, they meet with old acquaintances: Ugachi is an old college classmate who is now a police detective, though she's usually not a big fan of seeing her old friends again nosing around at her crime scenes. Another old college classmate is also in the business of crime, although that is literal: unlike the previous crime-fighting trio, Mikage has chosen the path of the criminal consultant, planning crimes for others to commit, and occasionally, their paths cross, finding themselves on opposite sides.
Knockin' On Locked Door is in a way a book with a very rigid formula, as the stories basically always utilize either a howdunnit or whydunnit focus, or a combination of both. The idea of multiple detectives with different methods can be fun, like seen in Morikawa's Hitotsu Yane no Shita no Tanteitachi ("Detectives Beneath One Roof" AKA Two Detectives and One Watson), where the two detectives were bascially the Ant and the Grasshopper. Or a book I only recently reviewed: Sailor-Fuku to Mokushiroku features the trio of Kyouko, Mizuki and Marii who all focus on different aspects of a crime: Kyouko focuses on the whodunit, Mizuki on the howdunnit and Marii on the whydunnit.This approach however is very different from Knockin' On Locked Door: in Sailor-Fuku to Mokushiroku, the three detectives focus on the same mystery, but from different angles. Knockin' On Locked Door however isn't about the angle from which a crime is examined, but it's the intrinsic type of the mystery that determines whether Touri or Hisame will take the initiative in the investigation. This sounds better than the actual execution however. For obviously, each story will still feature both characters and most stories try to have something to do even for the detective who is forced to play assistant, but it's seldom you really feel it was really necessary to split up the questions of howdunnit and whydunnit across characters, and the synergy between the two elements isn't always as strong.
In fact, it's the opening story Knockin' On Locked Door that does this the best, and while this sounds very negative (don't worry, the book is overall really good), I did think it a shame the book almost peaked right at the start. The two detectives are asked to investigate the death of an artist, who was found murdered inside his locked atelier. Which doesn't make sense, because why wasn't the death dressed as a suicide if it was in a locked room anyway, and why were the paintings thrown across the floor and only one of them painted red? Thus we have a mystery that is both a locked room (the impossible) with very weird features (the inexplicable). The synergy between these two elements is at its best in this story. While the exact why is rather hard to guess, but the way how the why actually explains how the locked room was executed is brilliant, and the trick behind the how is quite clever, yet simple too. Together with the next story, the best story in the collection.
The second story, Kami no Mijikaku Natta Shitai ("The Dead Body Whose Hair Was Cut Short") I already read back in 2017 because it was featured in an anthology. The leader of a small theatrical troupe was found murdered in the small, soundproof apartment the group had been renting for their rehearsals. The body was discovered in the bathroom, wearing only her underwear and for some reason, her long hair had been cut short and been removed from the crime scene. Evidence seems to be pointing towards someone among her three fellow members, but why would anyone want to cut the victim's hair off? A case that is about the inexplicable, and the problem of the cut hair reminds of a certain mystery novel by a well-known Japanese author, the story itself is glad to tell you. I liked the story back in 2017 and now I still do, being very much a story done in the Queen-style as you'd expect of Aosaki. So a focus on physical clues and the state in which they are found, which tells us about what the culprit did or did not do. Some parts of the mystery might require a bit more imagination/guesswork than you'd usually see in a story in that format, but overall, the explanation of why exactly the culprit took the victim's hair with them and why she was left in her underwear in the bathroom is really good, and the story is despite it short length constructed really well.
Dial W Wo Mawase! ("Dial W!") has a title that is a play on the Japanese title of Dial M for Murder and starts off with two different clients appearing at the agency, so Touri and Hisame have to split up and work on different cases: Touri is looking into the death of an old man who seemingly tripped and died on the street during a midnight stroll, while Hisame has to examine an old safe, which for some reason doesn't open despite its now deceased owner actually left clear instructions as to how to open the safe. The story is again short, so it doesn't really surprise when we later learn the two cases are connected, and I do think the connection is really clever: the death of the old man and the safe intersect in a very interesting manner, and logically explains why both events have occured. The reason why I don't think this story is as strong as the previous two is mainly because the initial split in "two" cases seems rather too obvious, as you just know right away the two things will connect in one way or another, and because the first half of the story focuses at two different investigations, things move rather fast and feel a bit underdeveloped, even in comparison to the other (all very short) stories.
Cheap Trick has Touri and Hisame investigate the murder of a company executive, who had been afraid for his life for a while. He was shot with a rifle in his study through the window, but because the man had been expecting an attempt at his life, he had thick, black-out curtains hanging in front of the windows, making it impossible for anyone outside to snipe them. Yet the man was shot in his study in his chest and found lying near the window, even though he was avoiding the window all this time. So how did the sniper standing beneath the window know the victim would be near the window to be able to shoot him, despite the curtains? It turns out this murder was planned by Mikage, Touri, Hisame and Ugachi's old classmate who know engineers murders for others as a consultant, making this case a personal thing too. Like the title suggest, this one is a pretty cheap trick, in the sense it's fairly simple to guess. Aosaki tries to make it a bit more difficult by adding one element, but even that's a bit too obvious. Not the strongest story in the collection.
Iwayuru Hitotsu no Yuki Misshitsu ("A Locked Room in the Snow In a Way") has Touri investigate the death of a man who was found with a kitchen knife in his chest lying in the middle of the snowy field that lied between his own workshop and that of his brother, with whom he had a big row. The only footsteps in the field are those of the victim (and the persons who found him in the morning) and there are no fingerprints on the snow. A classic no-footprints-in-the-snow set-up, and as you may expect, a lot of the story revolves around Touri proposing many familiar solutions (using the knife as a projectile etc.) to this old trope which get rejected until they arrive at the real solution. Which isn't super exciting on its own, but I have to say the misdirection going on in this story is fairly good, making a solution which without the context would be very disappointing, still a story that is saved by competent plotting.
Juuendama ga Sukunasugiru ("Too Few 10 Yen Coins") is perhaps better translated as The Ten Yen Coin, because it's a play on the Kemelman story The Nine Mile Walk. This story is the odd duck out, not following the usual story format. Agency assistant/housekeeper Kusuriko tells her employers about a strange phone call she happened to overhear, of a man on his smart phone. The line she remembers is "I have too few 10 yen coincs. I need five more." The line stuck with her because the 10 yen coin is worth so little (100 yen is basically the equivalent to 1 euro/1 dollar), so in what situation would you need specifically 10 yen coins, and in such an amount the caller would say they had too few of them and needed five more? Like The Nine Mile Walk, this initiates a discussion that allows the two detectives to come up with various explanations for this specific line and the intended use of these 10 yen coins, taking in account the precise context of the phone call Kusuriko overheard. It takes a long time for the detectives to arrive at the explanation which seems rather obvious to me, though I guess people who are much younger than I might find it more surprising? It's a story that may have been more surprising many years later from now, but I find it hard to believe that it's that hard to guess what this is about.
Kagirinaku Kakujitsu na Dokusatsu ("A Poisoning with Extreme Certainty") is about the death of a politician, who collapsed after drinking his glass of champagne during a speech. Poison was detected in the remainder of the champagne, but a check of the security footage shows nobody forced that specific glass of champagne on the victim, nor did anyone have any chance to put any poison in the glass after it had been picked. The murder is once again the work of Mikage, making this another personal case. Perhaps the least memorable story of the collection, and unfortunately, also the last story. The how of the poisoning can be guessed very quickly once you get through the initial investigative scenes, and from there it's basically a problem-free race to the finish. There are interesting ideas to the crime as regards to some of how it was all timed by the planner of the crime, but still, once you realize how it was done the rest of the mystery falls like a set of dominos.
But looking at the whole collection, I'd say Aosaki did a good job with Knockin' On Locked Door on the whole. If you're looking for depth however, this might not be your book: each story is really short (though usually structured well), with the characters basically just doing their usual two catch phrases/the same comedic act or something like that at the start of a story before moving on to the main mystery, but most of the mysteries are plotted well, and while I do think the book peaked with its opening stories, it's an excellent read if you're looking for something easy to read and yet crave puzzle plots.