The Devotion of Suspect X is a 2005 mystery novel written by prolific Japanese author Keigo Higashino. The novel is the first in his loose "Detective Galileo" series, about brilliant but eccentric physics professor Manabu Yukawa, who is frequently consulted for advice on tough cases by his old schoolmate Detective Shunpei Kusanagi. In Higashino's native Japan, it won the prestigious Naoki Prize, one of Japan's most highly regarded literary accolades (Koji Suzuki, the author of The Ring, is also a notable nominee of the award). After it got an English translation in 2011, it went on to be nominated for the equally prestigious Edgar Award from the Mystery Writers of America, and helped put Higashino on the map in the English-speaking world.
Like most great mystery stories, it begins with a sudden act of shocking violence. Humble bento shop employee Yasuko Hanoaka, a single mother, stumbles into an unexpected confrontation with her abusive ex-husband Shinji Togashi after years of trying to escape him. When Togashi crosses the threshold of her home and tries to threaten her teenage daughter, Yasuko fights back in desperation, and is ultimately forced to kill him in self-defense. Faced with an impossible choice between confessing and covering up her crime, salvation arrives from a most unexpected source: Yasuko's neighbor Tetsuya Ishigami, a quiet loner who teaches mathematics at the local high school.
With eerie precision, Ishigami deduces Yasuko's crime in mere minutes—but instead of phoning the police, he offers to help her cover up the crime without question. Days later, Yasuko is prepared to face the inevitable police investigation with an airtight alibi, thoroughly baffling Kusanagi when he deduces Togashi's identity and fingers Yasuko as the most likely suspect in his murder. But when Kusanagi goes to his old friend Yukawa (called "Detective Galileo") for advice, things take an unexpectedly personal turn. Why? Ishigami and Yukawa were once schoolmates at Tokyo's Imperial University, and both men are well-acquainted with how the other thinks. As the mystery races towards its conclusion, it becomes clear to Yukawa that he and his old friend have wound up on opposite sides of the law, and that Ishihami may have put his considerable analytical skills towards constructing The Perfect Crime. But why would a middle-aged math teacher want to cover up a crime committed by a complete stranger? And why does every piece of evidence point towards an explanation that couldn't possibly be true?
The general consensus is that it has one of the more shocking Twist Endings that you're likely to encounter in a mystery novel. If you want to experience the big twist as it was meant to be experienced, proceed with caution.
This novel contains examples of:
- Asshole Victim: Togashi is a textbook example. The entire plot is kicked off by his murder, but considering he's a slimy car salesman who moonlights as a domestic abuser, nobody sheds a tear for him. Averted by the innocent homeless man who the police thought was Togashi.
- Bad Guy Bar: Kusanagi is pretty thoroughly repulsed by the cocktail bar where Yasuko used to work. Considering it was a regular hangout for people like Togashi, his reaction is probably justified.
- Conflicting Loyalty: Kusanagi implores Yukawa to tell him the truth as the latter deduces, out of both his duty of a police detective and a concern for Yukawa after witnessing Yukawa's apparent emotional pain for holding the truth to himself. Yukawa agrees to tell him on the condition that Kusanagi will never acts on it within any official capacity. Kusanagi agrees to the term and is willing to keep the information to himself for some time, but secretly decides that he will pursue the leads identified by Yukawa's theory if Yasuko doesn't turn themselves in after an extended period of time, even if it will likely cost him his friendship with Yukawa.
- Chekhov's Gunman: The homeless squatters in the camp under the bridge by Yasuko's apartment. With the constant references to them in the narration, you just know they're going to be crucial to the story in some way. They are: it turns out that the body that the police found was one of them, cleverly made up to look like Togashi.
- Chekhov's Skill: Ishigami has martial arts experience, and he spends his spare time coaching the judo team at his high school. This comes in handy when he decides to ambush a homeless man and strangle him to death.
- Contrived Coincidence: Yukawa only ends up solving the mystery because he recognizes Ishigami as his old friend from university, and he deduces that he was the real murderer while catching up with him. If not for that, the mystery would have gone unsolved. Even Yasuko comments that the only failure in Ishigami's scheme is not counting on Detective Kusanagi and him having a mutual friend in Yukawa.
- It is even more so if you consider that Yukawa only becomes suspicious when Ishigami casually observes how Yukawa still has a full head of hair when they happen to look at their reflections on a glassdoor, which seems very out-of-character coming from Ishigami as Yukawa has known the man to not care about appearances. Yukawa reasons that Ishigami must be in a position where he suddenly has to worry about his own appearance - that he is in love, yet he remains strangely disinterested when talking about Yasuko and the murder of her ex-husband. That was the starting point of Yukawa's interest in the case. Up to that point, even Yukawa hasn't considered the possibility of Ishigami having anything to do with the case and is just happy to be reunited with an old friend.
- Crazy-Prepared: Ishigami prepares for every eventuality when he sets out to help cover up Togashi's murder. Taken to disturbing lengths when it turns out that he went so far as to murder an innocent homeless man to throw the police off the scent, and that he was fully prepared to turn himself in as the murderer in Yasuko's place. He knew that the police would eventually sweat the real murderer's identity out of him, so he made sure that he actually was the real murderer.
- Cultural Translation: In the English translation, Yasuko works at a "lunchbox shop" instead of a bento shop. If you're reasonably familiar with Japanese culture, though, it's pretty obvious that the "lunch boxes" are bento boxes.
- Driven to Suicide: It is heavily implied that Yasuko's daughter Misato attempts to commit suicide towards the end of story.
- Driving Question: Just why exactly is Ishigami, a logically minded maths teacher, so willing to go to extreme lengths to protect a woman he's never spoken to? The final chapter reveals the answer: It's because a chance meeting with Yasuko is what saved Ishigami from committing suicide.
- The Ending Changes Everything: The Reveal that everything Ishigami had done was actually an elaborate plot to frame himself for Togashi's murder, and that he had killed an innocent homeless man to accomplish it, casts virtually everything about him in a very different light.
- Exact Words: Ishigami technically didn't say that he killed Shinji Togashi, he just said that he killed the man that the police found by the water treatment facility, which is 100 percent true.
- Everyone Went to School Together: Kusanagi, Ishigami and Yukawa all went to Imperial University at the same time, but they studied in different departments (Kusanagi studied sociology, Ishigami studied math, and Yukawa studied physics).
- Evil Former Friend: Yukawa comes to see his old friend Ishigami as this, though he recognizes that he probably had good intentions for most of the things that he did.
- Foil: Much of the novel is focused on the contrast between the old friends Yukawa and Ishigami. Both of them are brilliant academics who end up on opposite sides of the law, with Yukawa trying to use his expertise to solve a murder while Ishigami tries to cover it up. And with their slightly differing career paths, Ishigami (a mathematician) is focused on the theory of mathematics, while Yukawa (a physicist) is more focused on their application.
- Foreshadowing:
- The first time Kusanagi inspects the crime scene by the river, he makes a comment to Kishitani, saying the fate of the investigation depends on how long it takes the police to figure out the victim's identity. Guess where everything goes wrong with the investigation ...
- When the police first examine Togashi's corpse, they come to the conclusion that Yasuko couldn't possibly have acted alone in his murder because she's too small to have overpowered him by herself, and the strangulation marks seem to have been left by a taller man. This is made to look like a mistake by the police, but they're actually right: the corpse isn't Togashi, and Yasuko really didn't murder him—Ishigami did.
- Early on in the investigation, Kusanagi has a conversation with Yukawa during which the latter says he is not suggesting "that the police had made a mistake identifying the body".That is exactly what has happened.
- The repeated references to the unsolved "P=NP" problem. The problem poses the simple question "Is it easier to solve a problem, or to determine whether someone else's answer to that problem is correct?" Or in other words: is it easier to solve a murder for the police, or to prove that they've been trying to solve the wrong man's murder all along?
- Ishigami tells Kusanagi that his math tests are so hard because he likes to take advantage of his students' assumptions, often making problems look like they're a different kind of problem than they really are. His scheme uses that principle too: once the police have a motive and a suspect for Togashi's murder, they never question their basic assumption that the murder victim is really who they think he is.
- Coincidentally, Kusanagi later hears Yukawa talking to a student about tunnel vision because the student assumes he should use one theory to explain an experiment process when in fact it suits a different theory better. Kusanagi comments on how similar Yukawa's thought process is to Ishigami's, which prompts Yukawa to discover what Ishigami's real scheme is.
- Heroic Sacrifice: Yes, Ishigami does some pretty questionable things, but that doesn't change the fact that he's fully willing to go to prison for life so that Yasuko can keep her freedom, and that he was planning to do that all along. Almost everything that he did was to make the police suspect him of Togashi's murder instead of her.
- If I Can't Have You…: Ishigami does not take kindly to finding out that Yasuko is seeing Kudo, after he risked everything to help her beat a murder rap. Then ultimately subverted: he's much better at handling rejection than the police assume; his anger was an act to make it seem more likely that he murdered Togashi.
- Kansas City Shuffle: How Ishigami manages to outsmart the police. While they're investigating Togashi's murder, they never once suspect that the corpse isn't really Togashi, and that the real Togashi was murdered a day earlier than they think he was. And while they're trying to find holes in Yasuko's alibi, they never suspect that it's the corpse itself that they should be suspicious of.
- Love Makes You Crazy: Ishigami's love for Yasuko drives him to do some pretty crazy things. Subverted in one particular instance, though: he didn't kill a homeless man because he was crazy, he did it because he genuinely thought it was the only way to help Yasuko beat her murder rap.
- Meta Twist: The novel's central crime is clearly established the be murder of Togashi and its subsequent cover-up, with the mystery being "what did Ishigami do". This genre-standard setup ends up hiding the fact that there is a second murder in the mystery.
- Not So Stoic: Ishigami is an unflappable mathematical genius who can handle the sight of a dead body without batting an eye, but he's also deeply in love with Yasuko, and pretty insecure about the thought that she'll never love him back.
- Red Baron: Ishigami and Yukawa both have them. "The Buddha" and "Detective Galileo", respectively.
- Refuge in Audacity: Ishigami's plan utilizes this. He kills a homeless man and conceals his identity, but leaves just enough evidence to make the police think he was Togashi—thus throwing off their investigation by a day, and giving Yasuko time to prepare an airtight alibi. His scheme hinges on the police's assumption that nobody would ever be crazy enough to cover up a murder with another murder.
- Shadow Archetype: Ishigami is essentially a dark mirror of his old friend Yukawa, showing us how he might turn out if he ever gets so immersed in the academic world that he loses touch with his human side.
- Stalker with a Crush: Ishigami to Yasuko. He has a pretty unhealthy habit of showing up at the bento shop just to see her, he's been known to give her unwelcome phone calls, and he quickly turns hostile when he finds out she's seeing Kudo. Then ultimately subverted: he's in love with Yasuko, and his love for her can be pretty obsessive and one-sided, but it's a lot more innocent than it seems. He's just pretending to be a stalker so that the police will suspect him of Togashi's murder instead of her.
- The Stoic: Ishigami's defining trait. He sees everything in the world in terms of mathematics, and absolutely nothing can phase him. But not even he's immune to love, as it turns out.
- Sympathetic Criminal: Yasuko and Ishigami are undeniably criminals, but all of their actions are completely defensible: Yasuko killed her abusive ex-husband in self-defense, and Ishigami just wants to help her avoid getting sent to prison. Or so it seems: Ishigami's plan to help Yasuko involved murdering a homeless man, which not even his old friend Yukawa can defend.
- Taking the Heat: At the climax, Ishigami surprises everyone by calling the police and confessing to Togashi's murder, getting Yasuko off the hook. Then subverted after The Reveal: he really is the culprit they're looking for—but the murder victim isn't who they think he is.
- Tragic Villain: Ultimately, all Ishigami really wanted was to be loved. That doesn't change the fact that he killed an innocent man, which he fully realizes is an unforgivable crime.
