The Devotion of Suspect X

In a brief flashback, Ishigami recalls first meeting Yukawa in college when the two took an upper-level mathematics course together. At the time, Yukawa remarked on a complex equation that Ishigami was working on, and Ishigami was impressed because no one else recognized it, let alone understood it. The equation dealt with a 1970s math theory from Paul Erdos, who believed that the best, most accurate theorems would always be clear, simple, and “naturally elegant” (81). Ishigami’s entire way of thinking centered around this belief. After this introduction, the two discussed math and science often. While Yukawa was knowledgeable in other areas, such as literature and history, Ishigami only cared about math. They liked and respected each other, but eventually their paths diverged. Ishigami specialized in high-level abstract math, and Yukawa focused on applied physics.

As the narrative returns to the present, Ishigami invites Yukawa inside to talk and reminisce. Yukawa confesses his shock at the realization that Ishigami is teaching high school rather than doing research in a university. Ishigami does not want to talk about the difficulties that led him here and shrugs off the comment. Then Yukawa mentions that his friend, Kusanagi, is the reason he found Ishigami. Ishigami pretends not to be concerned by this news, but privately, he fears that Yukawa’s brilliance might lead him to notice something in the case that Kusanagi has missed, which he will no doubt share.

Yukawa offers Ishigami a complex math equation to test his skills. Ishigami spends several hours working on it, forgetting Yukawa is still there. He enjoys the work, thinking of math like “a treasure hunt” (88). By the time he finishes, it is morning.

Yukawa joins Ishigami on his walk to school. He again asks about Yasuko and the murder case, but Ishigami claims not to know anything. Ishigami adds that he does frequent the lunchbox shop where Yasuko works, though he did not think to mention that to the police. He hopes that making this statement now will allay any lingering suspicions about his earlier omission. They follow the same route that Ishigami takes every day along the river, and Ishigami sees the Can Man as always. Ishigami worries that Yukawa’s presence will fluster Yasuko at the shop, but just before they reach Benten-tei, Yukawa leaves. Relieved, Ishigami walks into the shop.

Yasuko is relieved when Ishigami arrives. She tries to talk to him about the case, but Ishigami warns her that someone might be watching. Carefully, she remarks on his late-night visitor, worried that the police were questioning him again. When he explains that he had a visit from an old college friend who has nothing to do with the situation, she calms down. Ishigami then leaves and heads to the school. Meanwhile, Yasuko’s employers tell her that the police came to question them as well; they are angry on her behalf and are shocked that the police would suspect her of anything.

Suddenly, a man named Kuniaki Kudo arrives. He was a customer at Club Marian, where Yasuko used to work. Kudo explains that he saw the news about Togashi and recognized him as Yasuko’s former husband, so he came to offer her his support. Yasuko recalls that Kudo requested her company often at the club and they became friendly. She liked him and he was kind, but their relationship was always platonic because he was married and she did not want to risk an illicit relationship.

Now, Kudo asks her out for coffee, and she accepts. He commiserates with her over the horror of the situation and asks her out to dinner. He then gives her a ride home in his car. When he drops her off at the apartment complex, Ishigami is outside and watches her exit the car and walk into the building. A few minutes later, Ishigami makes his usual call from the payphone. He asks if there are any updates, and she says nothing. After they hang up, she wonders if she should have explained who Kudo was. She fears that Ishigami might believe that she owes him; she fears that he will hold his help over her head forever, preventing her from dating anyone.

Again, Kusanagi visits Yukawa to talk about the case. Yukawa seems more interested than he usually does when Kusanagi comes to complain about work, and the detective is immediately suspicious. Yukawa claims that he is merely curious about the problem of the “ironclad alibis” (109). Kusanagi talks through his thoughts, admitting that they have no real proof Yasuko is involved, but they also have no other viable suspects, and his intuition tells him that she is involved.

Yukawa chips away at the details of the case. For instance, it makes no sense for the murderer to destroy the fingerprints but leave the bicycle with fingerprints on it behind. He also thinks it is odd that the bicycle was stolen. He notes that Yasuko could not have killed Togashi alone, as she is too small to overpower him. Kusanagi concedes that it is possible she had an accomplice; they are currently looking into other men in her life. He supposes that her former work as a club hostess means there might have been many men in her life, but Yukawa points out that this is a sexist assumption.

Elsewhere, Ishigami gives his students a math test, ignoring their complaints that the work is too advanced. He wonders why he is there and feels that he is wasting his time. After school, Yukawa meets him and leads them toward Benten-tei, saying that he wants to buy a box to take home for dinner. Inside, Yasuko is clearly surprised to see Ishigami, but she recovers quickly. Then Kudo walks in, and Ishigami recognizes him as the man who dropped Yasuko off the night before. He is filled with jealousy as he watches Kudo speak casually to Yasuko. Then he and Yukawa leave.

Outside, Yukawa explains that his friend Kusanagi suspects Yasuko but cannot prove it. The police want Ishigami to report on Yasuko’s movements and behavior. Yukawa says he thought that the request might be better coming from him. Ishigami refuses, insisting that he does not know anything about the murder and does not want to be involved. Before Yukawa leaves, he poses a new math equation for Ishigami, asking, “Which is harder: devising an unsolvable problem, or solving that problem?” (126).

Yasuko goes out to dinner with Kudo. He explains that his wife died a year ago, and he asks to date Yasuko formally. He would even like to meet her daughter. Yasuko hesitates, worried about how Ishigami might react, but she finally agrees, feeling genuinely happy around him. When she returns home, a knock on the door startles her. She fears that it is Ishigami, but it is the junior detective, Kishitani. Apologetically, he admits that the police are watching her movements, and he asks about the man she was just with. Angrily, she explains who Kudo is. Kishitani also asks how long Yasuko has owned her kotatsu, trying to sound casual but failing. After he leaves, Yasuko receives her usual call from Ishigami.

The narrative reveals that Ishigami waited until he saw the detective leave before he walked out to the payphone to make his call. Based on Kishitani’s questions, Ishigami surmises that the police have figured out the murder weapon was a kotatsu electrical cord, and that they suspect a male accomplice might have been involved. However, he is not concerned and tells Yasuko so.

At the police station, Kusanagi confirms that Kudo only approached Yasuko after the murder; it is therefore unlikely that Kudo was Yasuko’s accomplice. However, Kusanagi’s chief suggests that the two could have been engaging in a relationship secret before; the chief recommends monitoring Kudo to be sure. Kusanagi is frustrated because earlier that day, while staking out Benten-tei, he had been shocked to see Yukawa walking with Ishigami into the shop.