I'm writing this review literally over four months after reading the book. There's also like three months between me writing this review now, and this review actually getting posted. I guess it fits the theme of clocks and time...
The first story Yuruyakana Jisatsu ("A Slow Suicide") is quite short and apparently, I already knew this story as it was adapted as part of the 2014 television special of the Kagi no Kakatta Heya drama series, but to be honest, I could remember absolutely nothing of the tale. Enomoto finds himself dragged to a yakuza office, where he is forced to open a door. Earlier, the yakuza captain Nonogaki left his low-level grunt Mitsuo alone in the office, but just as Nonogaki was greeted by his driver and about to get in the car, a shot rang out from the office. With the entrance locked from the inside and the office being very well secured, the daughter of the head of the organisation decides to bring Enomoto in to pick the lock for them, a job Enomoto would rather not do as it's obvious he's getting involved in stuff he doesn't want to get involved with, but he has no choice. When he opens the door, they find Mitsuo alone and dead inside the office, with a pistol in his hand and a hole in his head. Mitsuo's death has parallels with the death of a rival captain of Nonogaki who died earlier, and at first it seems Mitsuo commited suicide because he was somehow involved with that previous death, but Enomoto quickly stumbles upon a few contradictions at the scene that seem to indicate Nonogaki planned Mitsuo's death, but how could he have killed Mitsuo inside the locked office at the same time he was outside about to get in his car? Not a fan of the solution to be honest. The prologue already makes it clear Nonogaki is indeed the guilty one, but the question of how he managed to kill Mitsuo is a bit unsatisfying: it demands a lot of incertain/unpredictable actions from Mitsuo for example, and because the story is very short, it feels a bit forced too. More time for the set-up/foreshadowing might have helped the tale.
The titular Mystery Clock on the other hand is very, very long and almost closer to an actual novel than a novelette. Junko has been invited to the holiday villa of Mori Reiko, a famous mystery author and her client who is celebrating her thirtieth anniversary as a professional author. Other guests include her nephew, her first husband, her editor and... Enomoto Kei, who Junko brought along as a security expert to help make the villa safer, but she's terrified he's going to steal something. During the little party, Reiko goes upstairs because she has a deadline to meet and needs to finish her manuscript. She asks her current husband, the mystery author Tokizane Genki, to entertain the guests and he shows off her fabulous collection of antique clocks, including the transparant Mystery Clocks designed by Houdini himself. They play a game where the guests have to guess the relative values of the clocks, with the winner being awarded an antique clock, When the game is over, the whole party goes up to check on Mori Reiko, but they find her dead in her study. Her husband Tokizane however suspects one of the guests killed his wife, and he grabs a rifle and threatens them all, hoping the murderer will confess. He eventually decides to have his guests deduce who the murderer is, rounding them up in the dining room and having them basically accuse each other based on the evidence they found earlier. Eventually Tokizane gives up and allows them to call the police, but by that time, Enomoto has more than a strong suspicion that Tokizane himself is the murderer. The only problem is that Tokizane's alibi is perfect: from the time his wife left the room until they found her body, his alibi was vouched for by five different clocks: the real time clock in the victim's computer, the radio-controlled clock in the main hall, a clock in the study and two clocks in the dining room including a grandfather clock. So how did he kill his wife when he didn't have the time?
The story does not pretend like it's a secret that it's inspired by Ayukawa Tetsuya's short story The Five Clocks (included in The Red Locked Room. Disclosure: I translated The Red Locked Room) as it even mentions it explicitly. But Mystery Clock is The Five Clocks on drugs. The moment the story starts, it keeps on making very, very clear that time is very important to this story. Every single timestamp mentioned in this story is bolded, to make it absolutely clear how long each event takes and at what time, and at the end of the first act, you'll realize that Tokizane couldn't have committed the murder as basically every second has been accounted for. And what makes Mystery Clock a lot trickier than The Five Clocks is that we have newer, modern clocks like satellite-linked clocks that can't be easily changed by hand. So how did Tokizane manage to find the time to kill his wife even the clocks say he didn't? Well, by an insane combination of different tricks to fool each seperate clock, but by the time you get to the end of the story, you'll just be exhausted as it's just too complex. Each of these tricks could have possibly worked as the single idea for a short story, but when thrown together it's just too much, and some of the trickery performed is almost too complex. Like with one of the final things explained: I could hardly make any sense of the written explanation of the trick, and I was happy to see the following page had a diagram to make things clearer... only it still took me a long time to really comprehend what that diagram, and the text earlier were trying to convey, and from a certain point on, you kinda understand that the ideas used in this story can be pretty interesting, but it's just told in an incredibly dry manner. It stops being a story and just feels like a puzzle.
Perhaps the story would have worked better if it had been adapted in a visual format, for while there is pretty ingenious story buried here, the many, many bolded timestamps just make the tale appear like nothing but a set of puzzle pieces and it results in a very tedious read. This is truly a story that's just too clever for its own good.
To be honest, I liked the two stories in Colossus no Kagizume a lot better than the two in Mystery Clock: the first story is just too short with an idea that doesn't really manage to impress, while the titular Mystery Clock is perhaps the other way around: it's way too ambitious, resulting in a story that is more like a dry puzzle than an actual story, with too much tricks packed into the tale of which some are just too clever for their own good. It's more a story where the author can show off his ingeniousness in plotting an imposssible alibi, rather than a story that is actually enjoyable for the reader to err, read. So if you had to choose only one of these two volumes which were released on the same day, I'd definitely recommend Colossus no Kagizume over this one.