Viewers of the anime adaptation of the manga and novels of Bungō Stray Dogs, both written by Kafka Asagiri, may remember this story – it was the source material for episodes six and seven of the first season. That shouldn't deter you from reading the book, however, because not only is it a good read in its own right, but it also digs deeper into the character of Doppo Kunikida, arguably the most straight-laced member of the Armed Detective Agency, by being written almost entirely in his voice. It's a rare chance to really get inside his head, and that's worth it all on its own.

The story takes place two years before the start of the main series, with Dazai's admittance into the Armed Detective Agency. At this point in time, no one there knows what his past is (although Ranpo almost assuredly has figured it out, he's not saying anything), and to Kunikida's eyes, Dazai's just a weirdo troublemaker. He's less than thrilled to be assigned as Dazai's training partner, but because he's nothing if not scrupulous and moral, he agrees to take on the task. Part of his job is to administer the Agency's “entrance exam” to Dazai, a test of skills (and character) to make sure that he's a good fit for the organization – and if Dazai harbors what the president calls “darkness in his heart,” Kunikida is to kill him. With this in mind, the two set out to solve the mystery of what happened to multiple tourists who seem to have just up and vanished while also pursuing leads provided by some bizarre emails sent directly to Kunikida.

While the mystery is important to the story – and largely told in classic mystery fashion adhering to the rules laid out by S.S. Van Dine and Ronald Knox – what the real treat here is is the character development. Because of his nature as “the responsible one” in the main storyline, we rarely get the chance to truly see behind Kunikida's façade, although the extra episode of season two and parts of season three are working to change that. Here, however, we're actually in his head, and that allows us to get to know the character through his first-person narration. What we find is someone who is struggling with himself – he prides himself on his punctuality, his carefully laid out plans (including for his life) and his devotion to his work at both the Agency and as an algebra tutor. Order is what gives him comfort, but he's also got a softer, more caring side that is willing to throw away apparent good sense when it rises to the fore, and he's uneasy with that part of himself. There's also a sense that he doesn't fully understand it, and this is where his partnership with Dazai proves to be a boon to him, even if Kunikida doesn't see it that way – Dazai's overt emotionality forces Kunikida to deal with messy emotions and actions in a way that he's largely avoided, and really to face them head-on.

Not that he does this without a fight, of course. This is most clearly seen in his relationships with two of the novel-only characters (meaning they don't return after this storyline), Rokuzo and Miss Sasaki. Rokuzo's father was killed during a joint mission by the Agency and several government groups, and Kunikida feels responsible for the boy, believing it to have been his fault that his father was killed. Despite this, he can't quite bring himself to take on the actual role of “father figure;” he can't quite vocalize why, but we can infer that feelings of guilt and care conflict with his desire for order and organization. Likewise meeting Miss Sasaki provokes a crisis of emotions versus reason for Kunikida – he's attracted to her, jealous of Dazai's easy rapport with her, but also mired in his own future plans (wife in six years and not before!) and unable to reconcile his emotions with that. It is these internal conflicts that give the book its bittersweetness, something that is both poignant and well done.

It also is a shout-out to the historical Doppo Kunikida, who began his writing career as a Romanticist and ended it as a Naturalist. The two schools of literature are essentially opposites – the Romantics believed in freely expressing emotions and wallowing in them, while the Naturalists (who arose as a response to the Romantics) focus on determinism, science, and rationality. Thus what we can read in the literary evolution of real-life Kunikida (potentially related to his early death from tuberculosis, which he may have been trying to reason with) in Bungō Stray Dogs' version can be seen as the character being in conflict with himself – he's at heart a Romantic, but yearns for the safety of Naturalism. This certainly can also be used in thinking about his relationship with Miss Sasaki as well, who in real life was Kunikida's wife…and whose mother encouraged her to kill herself rather than marry him.

“This is the record,” Kunikida says in the novel, “of the struggles between a man who yearns for the realization of ideals and a new hire destined to interfere with them.” On the surface, that's certainly a good way to sum up the story. But there's more to it than that. Over the course of the book, Kunikida has to face up to the idea that his ideals may be more guidelines than a roadmap, and that sticking too closely to them may not be the best plan. Interference, he learns, is not always the worst thing, even if it isn't always something you're ready to look at head-on.