Now I think of it, I haven't reviewed that many collaborative works here. This one is a bit different of course, considering the two didn't really work together...
A pushy person in need of money manages to sell off some documents to a mystery writer, but it turns out these documents actually contains a rather interesting, and mysterious account of a murder and the writer decides to have the manuscript published. The documents consist of a series of long letters, be written by a Sobue Shinichi, a journalist, writing to a friend, who may be the person who ended selling the manuscript. Sobue tells about the horrendous murder on Anezaki Saeko, a beautiful widow who one day was found murdered on the second floor of the storehouse in the garden. However, not only was she found completely naked for some reason, the storehouse itself was found locked from the inside. Anezaki and Sobue were both members of a club headed by Kumauchi where they dabble in spiritualism. The testimony of a legless vagrant (who couldn't have come up the second floor himself) tells the police two people approached the house during the time of the murder, a gentleman and a woman in an old-fashioned kimono, but the police can't find out who these people are. At the club, Professor Kurokawa, the strongest believer in spiritualism, wants to hold a seance to look into the matter: he takes care of a blind girl with spiritual powers and who can act as a medium. During the seance however, the girl (while possessed) not only declares the murderer is among them, but also that the beautiful woman in front of her will also die, and there's only one person in the club who answers to this description...
Thus goes the story Akuryou ("Evil Spirits") by Edogawa Rampo, a story that was never finished. The story originally started serialization late 1933, long after it had been originally announced and hit by delays. Rampo even skipped serialization twice during this time, and ultimately, Akuryou was cancelled after only three installments, with Rampo citing "various reasons" led to him giving up, including the fact he had started writing the story before the plot had been properly developed yet. In 2024, Ashibe Taku finally gave Akuryou a proper conclusion: his Rampo Satsujin Jiken - Akuryou Futatabi ("The Rampo Murder Case - Return of Evil Spirits", 2024) is a collaborative work with the late Rampo, containing not only the original three installments of Akuryou, but also including an original ending by Ashibe, clewed together by him based on the three existing installments. And not only that, Ashibe even offers an explanation to why Rampo gave up on the project in the first place...Rampo Satsujin Jiken - Akuryou Futatabi is in many ways a very special book. It basically tells two stories on two layers: it has the original unfinished Akuryou manuscript by Edogawa Rampo, which of course tells a story on two levels: the story of the detective writer who bought the manuscript, and the story within those letters (the Anezaki murder). Ashibe too finishes these two stories on both levels, and even adds an extra layer to the story that explains why Rampo ended up cancelling this serialization. The result is a story that jumps back and forth a few times, and which can be confusing at first, but things do come together in the end.
What caught my attention at once was the physical element of the book by the way. Publisher Kadokawa uses very different fonts to differentiate the various elements of the story, so you can instantly see whether you are reading the original serialized Akuryou pages, or the new original pages by Ashibe. The font used in the Akuryou parts do really look like the font used in older early Showa publications (and even look slightly smudged like you're really reading an old book), and it really helps sell the vibe of reading an old, genuine Rampo story.
Anyway, it is very hard to judge this book on its merits as a mystery story. Fact remains that Edogawa Rampo abandoned the story mid-way and left no notes as to indicate how the story was supposed to end, so all Ashibe could do was use whatever was already there: he had to play detective himself, find the clues Rampo left and find out the solution himself! Of course, Ashibe had more creative freedom than a real detective: it wasn't as if he had to build the solution solely on the elements featured in the first three installments, as he was able to freely add segments retroactively, but still, Ashibe of course tried to keep the "original" Akuryou intact as much as possible, and have his solution stick as close as possible to the original Rampo manuscript. That is what makes this a difficult story to judge, because Ashibe's hands were tied.
Some parts of the mystery, like the locked room murder of Anezaki Saeko, were already quite fleshed out in the original script, and Ashibe is able to put forward a solution that seems well grounded in Rampo's work, but other parts of the original mystery must have been more troublesome to Ashibe, like the mystery of a curious drawing on a note found inside the locked room: attributing a meaning to that sketch in a way that ties it to the murder must have been an insanely strange challenge and while I do think Ashibe did a good job at providing an answer to it, the original idea of the drawing itself was never really that interesting to me as it always seemed to me the answer would feel a bit forced, or at least trivia-reliant, and Ashibe's answer doesn't stray far from that expectation. In a way, that's of course impressive: it definitely feels like Rampo... I know from experience that some of Rampo's serialized longer works often feel like he didn't plan that much in advance, and often his set-ups for mysterious events were much better than the solutions he'd later provide. In a way, I feel Ashibe's conclusion to the story has elements of this too, but at the same time, I can't really blame him considering it was Rampo who set everything up, and Ashibe simply had to guess what the solution could be. And style-wise, I can't deny Ashibe managed to nail Rampo's work. He clearly studied Rampo's writing, so the additions don't feel out of place, and you could imagine this being the genuine ending to Akuryou. And in that sense, I do think Rampo Satsujin Jiken is an impressive work, more so than in the sense of it being a mystery story on its own.
Interestingly, it appears that even if this book were to win an award, the credits would likely go more towards Rampo than Ashibe. While the two authors share the credits on the cover, the bulk of the book consists of the original Akuryou manuscript, so that apparently has influence on who would be the main recipient of a hypothetical award, even if I do think the book's interesting exactly because of the transformation by a second author.
So Rampo Satsujin Jiken - Akuryou Futatabi is not per se a book I would recommend to a mystery fan, because as an standalone mystery novel, it is really mostly a 1930s Rampo serialized novel with all the haphazard planning and somewhat disappointing payoff to the set-up. However, with the surrounding context of Ashibe coming with an original conclusion based on the unfinished story, him emulating the style and offering an explanation why Akuryou was never finished, you get a story that is infinitely more interesting than Akuryou on its own. So recommended to Rampo fans, and people who want to see Ashibe live out his fanboy dream and finishing one of Rampo's work.