Most of the characters in the main Bungo Stray Dogs are dead. Or at least, the authors they're (loosely) based on are, and I have to think that that makes it easier for series author Kafka Asagiri to create their characters. But that's not the case for Bungo Stray Dogs: Another Story: Yukito Ayatsuji vs. Natsuhiko Kyōgoku. All three main characters are based on authors who are very much alive, three award-winning Japanese mystery writers whose works have been at least partially translated into English: Yukito Ayatsuji is the author of Another and The Decagon House Murders, Natsuhiko Kyōgoku is the author of The Summer of Ubume and Loups-Garous, and Mizuki Tsujimura is the author of A School Frozen in Time and Lonely Castle in the Mirror. In the afterword of the book, Asagiri explains that all three authors are fans of Bungo Stray Dogs and requested to be part of the story's world, but one gets the distinct feeling that Asagiri wasn't entirely comfortable with this.

Despite that, Another Story is one of the strongest novels in the franchise to date. It's in many ways an homage to classic mystery fiction, which makes sense when we consider Ayatsuji's most famous (in Japan) work, The Decagon House Murders and its sequel, The Mill House Murders. Both are distinct and intentional tributes to Agatha Christie (most notably her 1939 novel And Then There Were None), and Asagiri references them in the form of an old case novel Ayatsuji solved, involving a group of murderers on an island, while Another past case he solved deals with a house designed by a famous architect. But the most-referenced story isn't by any of the character-authors at all; it's Sir Arthur Conan Doyle's 1893 tale The Final Problem. As you likely know (either from reading or through cultural osmosis), this is the story where Sherlock Holmes and his nemesis Professor Moriarty plunge into Reichenbach Falls, resulting in their presumed deaths.

That's where the book opens: with Ayatsuji and Kyougoku poised at the top of a raging waterfall, which the latter ultimately plummets from. Ayatsuji (and everyone else) assumes that this means that Kyougoku is dead, because his Skill, “Possession Drop,” allows him to use unwitting people as his puppets, not to catch himself from a fall. Meanwhile, Ayatsuji's Skill is “Another.” It ties directly into his work as a detective, activating whenever he solves a murder so that the murderer will die in what appears to be an accident. Since Kyougoku has been proven to be a killer, the thought is that his death is simply “Another” at work.

But then he comes back.

Again playing with The Final Problem, the book's main plot revolves around Kyougoku's seeming return from the dead and how he continues to manipulate those who pray to him at shrines set up in liminal spaces. As you may be aware, real-life Kyougoku relies heavily on folklore in his novels and has stated that Shigeru Mizuki was one of his major influences as an author. That carries over into his fictional version, and part of the problem for the Special Division and Ayatsuji is working with this very unscientific premise. Yes, the characters in Bungo Stray Dogs live in a world where some people have special talents straight out of science fiction, but that's not fantasy. Every supernatural element in their world can be explained or quantified, and Skills behave in specific, predictable ways – even Tsujimura's Shadow Child, which even she doesn't fully understand. But folklore is different. It's rooted in unscientific belief, an accumulation of people believing the same story without any proof that it's true. No one goes around talking to kappa in Bungo Stray Dogs. Those aren't real.

One of the foundational elements of Kyougoku's worldview in the story is the idea of memes. Most of us know them as images of dogs sipping coffee as a house burns down around them or captioned cat photos, but memes originate in the idea of something replicating without genetics – things people simply share. All folklore, to a degree, is a meme, and Kyougoku's actions are all carried out with that in mind. His Moriarty is the more freewheeling counterpart to Ayatsuji's Holmes, someone not bound by norms and the burden of proof. Even Ayatsuji's Skill is in opposition to everything Kyougoku represents; his “Another” can't even activate unless he proves, conclusively, that someone is guilty of a crime.

Tsujimura's character is the Watson, one of the more bumbling incarnations of the type. But that doesn't make her useless or foolish. Yes, she's fully obsessed with secret agent movies (and imported herself an Aston Martin), but she's haunted by her mother's death in the island murder case five years before the book's opening, and she's determined even as she recognizes her shortcomings. She feels very much like the Atsushi of Another Story, providing a more human element among all of the overpowered greats, and Asagiri does a good job of incorporating her real-life counterpart's double-duty as both an adult's and a children's author into the finale. Her purpose is to ground the story, and she does that with aplomb.

Although Ango Sakaguchi is a minor character and Chuuya Nakahara gets a brief appearance, this book largely stands on its own. The epilogue mentions the fight against the Guild, so that's where this falls in the greater Bungo Stray Dogs timeline, but overall, you could probably get away with reading this as a standalone, and absolutely could if you're otherwise an anime-only fan. It's a bittersweet entry into the franchise, one that understands the appeal of mystery fiction and does its best to live up to it.