58 pages • 1-hour read
The Devotion of Suspect X
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Symbols & Motifs
Content Warning: This section of the guide includes discussion of gender discrimination, graphic violence, and death.
Mathematics
Mathematics is a major symbol that represents Ishigami’s worldview and approach to life, as well as the puzzle-like structure of the novel’s central mystery. First, math serves as the lens through which Ishigami views the world and his place within it. In Chapter 2, Ishigami analyzes Togashi’s death and his plan to cover it up as a math problem, reasoning that the “problem had a solution” because “[e]very problem had one” (37). He crafts his plan like a complex equation, setting it in motion like a series of formulas with variables that he can move and manipulate as needed in order to arrive at the solution he wants. This symbolism reappears throughout the novel, surfacing in Ishigami’s internal monologues, in his assurances to Yasuko that the police are behaving in accordance with his calculations, and in his rekindled friendship with Yukawa.
In Chapter 6, the narrative establishes that mathematics is the topic over which Ishigami and Yukawa bond in college. In this context, math symbolizes their friendship and their shared intelligence and their use of logic to understand the world. Yukawa rekindles this friendship by offering difficult mathematical proofs to Ishigami like a kind of game. And as Yukawa begins to suspect Ishigami, and Ishigami realizes that Yukawa is investigating him, math becomes the method by which they compete. When Ishigami’s plans begin to falter, he even compares Yukawa to part of an equation, thinking, “An elaborate formula he’d thought was perfect was now giving false results because of an unpredictable variable” (156). In this metaphor, Yukawa is the “unpredictable variable” for which Ishigami has failed to account.
Simultaneously, the characters’ use of mathematics symbolizes the plot of the novel. The “elaborate formula” that Ishigami describes is the case itself, including Togashi’s death, Ishigami’s plan, and the resulting police investigation. The symbolism is reinforced by Yukawa’s mathematical riddle for Ishigami in Chapter 8, when he asks, “Which is harder: devising an unsolvable problem, or solving that problem?” This question lies at the heart of the conflict between Ishigami and Yukawa, for Ishigami attempts to craft an unsolvable problem by devising the murder mystery, while Yukawa attempts to solve it.
The Engineer
In many ways, the unhoused man whom Ishigami mentally labels the “Engineer” functions as a symbol of the unaddressed and invisible truths that lie just beneath the surface of a mystery story. Just as the Engineer and the other unhoused people of the tent city are frequently overlooked and ignored by those who enjoy more abundant economic circumstances, his absence from the plot halfway through the novel proves to be a deeply sinister detail that hints at Ishigami’s own violent crime on Yasuko’s behalf. When Ishigami sees the empty bench upon which the Engineer used to sit, then quickly looks away, this seemingly unimportant detail obliquely emphasizes the man’s absence, which in time takes on a presence of its own when the truth of Ishigami’s actions later come to light.
However, the man’s invisibility to an uncaring society is challenged when Yukawa champions The Inherent Worth of Individuals and asserts that all people, no matter their station, hold value in the grand scheme of the world. Ishigami’s callous murder of the Engineer, which is based upon his assumption that the man holds no importance to the world, ultimately condemns him in Yukawa’s eyes, even though the physicist was willing to make moral concessions for Ishigami’s desire to protect Yasuko out of love. In this way, the Engineer also signifies the subtle but overlooked plot element in the typical “whodunit” mystery: the crucial point at which the entire illusion unravels.
Cogs
Though cogs do not appear in the novel until Chapter 15, they are a crucial symbol. Yukawa explicitly explains the symbolism of cogs when he states that each person is a cog in the clockworks of the world, and adds that “the world needs its cogs, all of them; and […] only a cog may determine its eventual meaning in the system” (219). He expands further when he shares his deductions with Kusanagi in Chapter 18. Through the symbol of the cogs, Yukawa argues that individuals have inherent value in the world, no matter how inconsequential they appear to others. This worldview assigns equal value to all people, including the unhoused people living in the tent city on the banks of the Sumida River, even though Ishigami treats them like faceless pieces in a game. Yukawa believes that Ishigami’s decision to murder one of those men is unforgivable.
Thus, cogs become an important component of the theme of Navigating Imperfect Justice and Moral Ambiguity. Although issues of morality are rarely never clear-cut and often leave room for interpretation and ambiguity, Yukawa argues that the inherent value of each person (or “cog”) is a moral constant around which Ishigami’s actions can and should be judged. Yukawa also believes that his comment about cogs was the idea that inspired Ishigami to turn himself in, presumably out of guilt. However, Ishigami’s internal monologue belies this interpretation. Rather than thinking about his own guilt, Ishigami realizes that Yukawa has solved his equation and decides that he must act quickly to protect Yasuko. He never actually regrets his decision to commit murder, believing his actions to be justified by his need to protect Yasuko.
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