Which meant, according to Yukawa’s theory, everything Yasuko Hanaoka and Misato had told them so far wasn’t their own, unsullied testimony, but one prepared by Ishigami, who had been behind them, pulling the strings the whole time.

  “Of course,” the physicist had added quietly, “this is all merely my conjecture—a theory constructed on the premise that Ishigami was somehow involved. That premise itself might be wrong. In fact, I hope it’s wrong. I hope deep in my heart that he had nothing to do with it.”

  Yukawa’s expression when he told Kusanagi this had been unusually pained—and, the detective thought, a little lonely. Perhaps the physicist feared losing an old friend so soon after becoming reacquainted with him.

  But Yukawa had never told Kusanagi the reason why he had come to suspect Ishigami in the first place. It seemed that he had somehow come to the conclusion that Ishigami had a crush on Yasuko—but he hadn’t mentioned any evidence he had to support that theory.

  Still, Kusanagi trusted Yukawa’s skills of observation and deduction, almost to the point that, if Yukawa thought something was so, the detective assumed it was correct unless proven otherwise. Which made what Kusanagi had heard at Club Marian all the more interesting.

  Why hadn’t Yasuko come to them with an alibi for the night of March 10? If she had committed murder and prepared an alibi, she would have wanted to tell them about it as soon as possible. But that might not be so if Ishigami had instructed her not to tell them. Maybe he had given them instructions to never say more than was absolutely necessary at any given time.

  Kusanagi remembered another remark Yukawa had made, back before he had shown any real interest in the case. When Kusanagi told the physicist that Yasuko Hanaoka had retrieved her ticket stubs from the movie pamphlet, what had he said?

  “If we assume that the tickets really were bought to establish an alibi, that she put them in the pamphlet expecting you to come and ask her for them, I’d say that makes her an adversary to be feared.”

  * * *

  It was just past six o’clock, and Yasuko was about to remove her apron, when a customer entered Benten-tei. She smiled and gave a reflexive “Hello!” in greeting, but when she saw the man’s face, she hesitated. It was a face she knew, but not well—that of Ishigami’s old friend.

  “Remember me?” he asked cheerily. “I came here before, with Mr. Ishigami.”

  “Oh, oh yes. I remember you,” Yasuko said, regaining her poise and her smile.

  “I happened to be in the area, and remembered your lunch boxes. The one I had the other day was really quite good.”

  “I’m glad to hear it.”

  “I’m thinking today I’ll … let’s have the special. I know that’s what Ishigami always gets, but you were out of them last time. How about today?”

  “No problem,” Yasuko said, giving the order to the kitchen and undoing her apron strings.

  “Oh? Were you on your way home?”

  “Yes. I work until six.”

  “Oh, I see. So, you’ll be going back to your apartment?”

  “Yes.”

  “Mind if I join you for a bit, then? There was something I wanted to talk with you about.”

  “Talk about? With me?”

  “Yes, well … I wanted your advice, I should say. It’s about Ishigami.” The man smiled.

  Yasuko grew uneasy. “Oh, I’m sorry but I hardly know Mr. Ishigami, actually.”

  “I won’t take much of your time at all. We can talk while we walk,” he offered, his tone soft but his words insistent.

  “All right, then, for a little, I suppose,” Yasuko replied, seeing no easy way out of the situation.

  The man introduced himself as Yukawa. He was an assistant professor at the university where Ishigami had studied.

  After a few moments Yukawa’s lunch box was ready, and the two left the shop together. Yasuko had ridden to work on her bicycle, as usual. Now as they set out down the street she pushed the bike along beside her, until Yukawa said, “Let me take that,” and began to push it for her.

  “So you’ve never talked much to Ishigami?”

  “Not much. Just a word or two when he comes to the shop.”

  “I see,” he said, and then fell silent.

  “You said you wanted some advice?” Yasuko asked. She felt the tension growing inside her.

  But Yukawa did not reply. Yasuko’s unease became a physical pain that spread across her chest and was starting to make her shoulders ache when finally he said, “He’s a simple man.”

  “What?”

  “He’s simple. Ishigami, I mean. I don’t mean stupid—I mean he’s straightforward, direct. The solutions he looks for in his work are always the simplest. He doesn’t start a problem by looking for many answers at once. And he always chooses a simple approach to get where he’s going. That’s why he is so good at what he does. There’s no indecision, and he doesn’t give up over trifling obstacles. It’s great for mathematics, but not so great for day-to-day life. You can’t always shoot for one result, for all or nothing. And yet he’s constantly doing just that, and winding up with nothing to show for all his efforts.”

  “Mr. Yukawa, I…”

  “I’m sorry, I know I’m not making myself very clear.” Yukawa smiled wryly. “Did you meet Ishigami for the first time when you moved into your current apartment?”

  “Yes, when I went around to meet my neighbors.”

  “And you told him you were working at the lunch shop then?”

  “I did; but why do you ask?”

  “I guess that’s when he started frequenting Benten-tei?”

  “I suppose it was, yes.”

  “I know you didn’t talk with him much, but did anything he said make a lasting impression on you? Any little thing?”

  Yasuko was confused. This was the last sort of question she had expected to hear.

  “May I ask why you want to know? Maybe if I knew, I could give you better advice.”

  “Well,” Yukawa shot her a sidelong glance as they walked, “it’s because he’s my friend. He’s a very important friend of mine, and I want to know how he’s been lately.”

  “I’m afraid we speak so little, there’s really nothing much to say.”

  “Yet for him, that connection to you was far more important than you make it out to be. I think you understand why.”

  Yasuko caught the serious look in Yukawa’s eyes, and it made her skin prickle. It suddenly occurred to her that this man knew about Ishigami’s interest in her and wanted to know why it had started.

  Yasuko realized for the first time that she had never given a moment’s thought to that herself. She knew from years of experience that she wasn’t the kind of beauty with whom men fell head over heels in love at first sight. It had to have been something else.

  She shook her head. “I’m sorry, but I can’t think of anything. Really, I could count the number of times we’ve spoken on one hand.”

  “I see,” Yukawa replied, his tone softening. “I suppose that makes its own kind of sense, doesn’t it?” Ishigami’s friend was mostly talking to himself, but then he turned to her again and asked, “What do you think of him?”

  “What?”

  “Surely you noticed his interest in you? What do you think about that?”

  Yasuko was taken aback by the directness of the question. She wished she could just laugh it off in embarrassment, but somehow that wouldn’t work in this conversation. “I’m afraid I don’t feel anything in particular—I mean, I’m sure he’s a good person. And he seems quite smart.”

  “Ah, so you do know him.” Yukawa stopped his feet.

  “Well, I wouldn’t say ‘know’ so much as that’s the impression I have of him.”

  He nodded. “Very well. Sorry to take up your time.” Yukawa handed off the bicycle. “Say hi to Ishigami for me.”

  “Oh, but I might not see him—”

  But Yukawa only nodded with a smile and turned away. Yasuko watched him as he left, wondering
how a man could make the simple act of walking away feel so intimidating.

  FOURTEEN

  Ishigami sat staring at a line of unhappy faces. Some of them were beyond unhappy—they wore looks of outright pain. A few had gone even further, and drooped in despondant resignation. One member of the dismal class—Morioka—hadn’t even glanced at the test sheet after Ishigami gave the go-ahead to start. He was staring vacantly out the window, head propped up on one hand. It was a nice day outside, with an endless expanse of blue sky stretched high over the school complex. Morioka was probably thinking about how he could be riding his motorcycle if he didn’t have to be in here, wasting time.

  The school and most of the students were already out on spring break. There was just this one group of students, with one final, depressing hurdle to jump. Too many kids hadn’t passed even the make-up tests after finals and had been required to do remedial class work. Thirty of Ishigami’s students were in these special classes—a far larger number than for any other subject. And after they were done with the extra coursework, another test awaited them: the re-make-up test.

  The head teacher had stopped by while Ishigami was writing up questions for the test, to make sure he didn’t make them too difficult.

  “I don’t like saying this, but really at this point the tests are just a formality. We can’t let the students go on to the next grade with failing marks. And I know you don’t like doing all these extra tests, either, do you? Besides, we’ve had complaints that your tests were too difficult from the beginning. Just—make sure everyone passes, okay?”

  Ishigami didn’t think his typical test questions were difficult. They were simple, in fact. There were no departures from the material he had covered in class. Anyone with half a brain, and a rudimentary understanding of mathematical principles, should have been able to solve them. Usually, all he did was change how the problems looked. Surely it would be too easy to use problems straight from the textbooks and practice sheets! Still, the students who simply tried to memorize answers and the ones who hadn’t paid any attention at all were at a loss when faced with basic challenges.

  So this time Ishigami had done as the head teacher instructed. He had used representative questions straight from the students’ practice sheets. Anyone who had studied even a little should have had no problem.

  Morioka gave a big yawn and looked at his watch. Then his eyes met Ishigami’s. Ishigami expected him to look away, but instead Morioka grimaced and held his hands up over his head in the shape of an X, as if to predict the mark that would be on this paper.

  Ishigami tried grinning at him. Morioka looked surprised, then grinned back, and resumed looking out the window.

  Ishigami remembered when Morioka had asked him what good differential and integral calculus was. Ishigami had used motorbike racing as an example, but he wasn’t sure if that got through to the boy. Morioka’s attitude didn’t annoy Ishigami. It was only natural to wonder why one had to study something. Once such questions were answered—well, then there was an objective, something to learn toward. And that could lead down the path toward an understanding of the true nature of mathematics.

  Yet too many teachers refused to answer simple questions of relevance from their students. No, Ishigami thought, they probably aren’t able to answer them. They taught without really understanding their subjects, simply following a set curriculum, thinking only of coaxing a passing grade from the students so they could send them on their way to make room for next year’s flock. Questions like Morioka’s would have been nothing but an irritation to them.

  What am I doing here? Ishigami wondered, not for the first time. Giving students tests just so they could earn points had nothing to do with the true meaning of mathematics. It didn’t mean anything. It wasn’t math, and it wasn’t even education.

  Ishigami stood and took a deep breath. “Wherever you are on your test sheets, you can stop.” He looked over the classroom. “I want you to turn your papers over and write down what you’re thinking right now on the backs.”

  Confusion washed across the faces of the students in the room. A mutter spread through the class. “What we’re thinking? What does that mean?”

  “Specifically, I want you to write down what you think about math. No,” he amended, “just write anything about math at all. You’ll be graded on what you write.”

  Every face in the room brightened.

  “What grade are you going to give us?” a male student asked.

  “Depends on what you write. If you can’t handle actual math, I hope you can at least say something about it,” Ishigami said, sitting back down in his chair.

  Every student turned over his or her paper. Some, including Morioka, began to write immediately.

  I’ll be able to pass them all now, thought Ishigami with some relief. There was no way to mark a blank answer sheet, but as long as they had each written something, he could assign grades as he saw fit. The head teacher might wonder a bit, but surely he couldn’t complain about Ishigami delivering the passing grades he’d specifically asked for.

  The bell rang, indicating the end of the test period. A few of the students asked for a little more time, so Ishigami gave them an extra five minutes.

  When it was done he collected the answer sheets and walked out of the classroom. The moment the door shut, he heard the room erupt into conversation. There were audible cries of relief.

  Back at the teachers’ room, a man—one of the office assistants—was standing just inside the door, waiting for him.

  “Mr. Ishigami? There’s someone here to see you.”

  “To see me?”

  The assistant walked up to him and whispered in his ear. “I think he’s a police detective.”

  Ishigami sighed.

  “What are you going to do?” the assistant asked, peering at him intently.

  “What am I going to do? He’s waiting for me, isn’t he?”

  “Yes, but I could tell him you’re occupied and send him home.”

  Ishigami chuckled. “No need for that. Where is he?”

  “The parent conference room.”

  “I’ll be right there.” Stashing the test answer sheets in his bag, Ishigami made his way toward the conference room. He would have to grade them at home later.

  The assistant started to follow him, but Ishigami waved him away, saying, “I’ll be fine on my own.” He knew well enough what the assistant was up to. The man wanted to know why the detective was there and had only suggested that they give the detective the brush-off in hopes that Ishigami would tell him what the visit was all about.

  The man Ishigami had expected to see was waiting for him in the conference room: the detective named Kusanagi.

  “Sorry to bother you here at school like this.” Kusanagi stood and bowed curtly.

  “I’m not usually here over spring vacation. I’m surprised you found me.”

  “Actually, I dropped by your apartment first, but it seemed you were out so I called the school. They said something about a make-up test? You have to give make-up tests during spring break?”

  “It’s worse for the students, I assure you. And today wasn’t a make-up test. It was a re-make-up test.”

  “You don’t say. Let me guess: you like putting pretty tough questions on your tests.”

  “Why do you say that?” Ishigami asked, looking the detective in the eye.

  “Just a feeling.”

  “They’re not tough, though. I merely take advantage of the blind spots created when students assume too much. And they usually assume too much.”

  “Blind spots?”

  “For instance, I give them a question that looks like a geometry problem, but is in fact an algebra problem. If all they’ve done is memorize the problem sheets in their books—” Ishigami abruptly stopped talking and sat down across from the detective. “I’m sorry. I’m guessing you didn’t come here to talk about high school mathematics. So, why are you here?”

  “Nothing much, really,”
Kusanagi said, joining him at the table and pulling out his notepad. “I just wanted to ask you about that night again.”

  “By ‘that night,’ you mean…?”

  “The tenth of March,” Kusanagi said. “I believe you’re aware that’s when the incident occurred?”

  “You mean the body they found by the Arakawa River? That one?”

  “Not the Arakawa, the Old Edogawa,” Kusanagi corrected him without missing a beat. “You may remember me and my partner coming to ask you questions about Ms. Hanaoka? Asking if you’d noticed anything peculiar that night?”

  “Yes, I remember. And I’m pretty sure I told you I didn’t recall anything out of the ordinary.”

  “That’s right, you did. I was just hoping you could try to remember that evening in a little more detail for me.”

  “How do you mean? It’s hard to remember something when nothing happened.” Ishigami let himself smile a bit.

  “Right, but what I’m looking for—or what I was hoping to find—was something that maybe you didn’t pay particular attention to at the time, but might actually turn out to be a valuable piece of evidence for us. Maybe you can just tell me about that evening in as much detail as possible? Don’t worry if it has nothing to do with any incident.”

  “All right. I suppose,” Ishigami said, scratching the back of his neck.

  “I know it was a while ago now, so I brought something I thought might help you remember the day.” Kusanagi handed over a chart of Ishigami’s work schedule for the week of March tenth, showing a list of the classes he’d taught along with the school events schedule. He must have procured the information from the office. “Does anything here jog your memory?” the detective asked, smiling.

  The moment he looked at the chart, Ishigami understood what the detective was up to. He wasn’t here about Yasuko Hanaoka, he was here to establish Ishigami’s alibi. Though Ishigami couldn’t say for certain why the police were suddenly turning their eyes in his direction, he suspected it had something to do with Manabu Yukawa’s strange behavior.