Ishigami had never told her what he’d done with Togashi’s body. He had said she didn’t need to worry about it. I’ve handled everything, he had told her over the phone in that calm voice of his.

  She had wondered why the police kept wanting an alibi for the day after Togashi was murdered. Even before the detectives had come, Ishigami had given her explicit instructions about what she was to do on the night of the tenth. The movie, ramen, karaoke, and even the late-night telephone call. She had done everything according to his instructions, not knowing why she was doing any of it. When the detectives asked about her alibi, she had told them exactly what she had done, but in truth she had wanted to ask them: why are you asking me about the tenth?

  Now it all made sense. Ishigami had led them into a trap. And yet, what a terrible trap it was. Even though she realized that there could be no other explanation, she still didn’t believe it. No, she didn’t want to believe it. She didn’t want to think Ishigami had done what he had done. She didn’t want to think about how he had thrown away his life for an average middle-aged woman with hardly any redeeming qualities, and certainly no great allure. Yasuko didn’t think her heart was strong enough to accept such a sacrifice.

  She covered her face in her hands. She wished her mind could stop working. She didn’t want to think about anything. Yukawa had said he wouldn’t tell the police. It was all conjecture—he didn’t have any proof. It was up to her to decide what was to be done. He had given her a choice. A spitefully cruel choice.

  Uncertain of what she should do, and lacking even the strength to stand, she crouched, frozen like a twisted stone, while the long minutes crawled by.

  Suddenly someone tapped her on the shoulder. Her head jerked upward.

  Someone was standing by the bench. Her eyes focused and she realized it was Kudo looking down at her, concern on his face.

  “What’s wrong?”

  It took her a while to understand why Kudo was there. She stared blankly up at him for some time before she remembered that they’d planned to meet. He must have come looking for her when she wasn’t at the restaurant.

  “I’m sorry. I was … tired.” She couldn’t think of a better excuse than that. And it was true. She was exhausted. Not her body, but her soul.

  “Are you sick?” Kudo’s voice was gentle.

  Too gentle, to Yasuko’s ears, and entirely out of place. Not knowing the truth could be a crime in and of itself, she realized. A crime she had been committing until only moments before.

  “I’m … all right.” Hesitantly Yasuko stood. She wobbled, and Kudo offered his arm.

  “Did something happen? You look pale.”

  Yasuko shook her head. She couldn’t explain what had happened. Not to him. Not to anyone.

  “It’s nothing. I felt a little queasy and had to rest. But I think it’s passed now.” She tried to sound confident, but lacked the strength.

  “My car is parked right over there. Do you want to rest a bit first before we go?”

  She met his eyes. “Go where?”

  “I’ve made reservations at a restaurant. I told them seven, but I don’t think it will matter if we’re a half hour late.”

  “Oh.”

  The very word restaurant sounded like something alien. Would she have to go to a restaurant and eat now? Would she have to pretend to smile with this black lump in her chest? Smile, and nod, and daintily wield her fork and knife? Not that any of this was Kudo’s fault.

  “I’m sorry,” Yasuko whispered. “I don’t think I can. Not tonight. I think I need to take a rain check until I’m feeling better. Today I am … I’m just…”

  “Hey, it’s okay,” Kudo said, patting her arm. “I think you’re right. It’s no wonder you’re tired, with all you’ve been through. Rest today. You probably haven’t had a chance to really rest for some time. I should have left you alone. It was thoughtless of me. I’m sorry.”

  Yasuko looked at Kudo, marveling at how genuinely nice he was. He truly cared for her. It made her sad to wonder why she couldn’t be happy with so much love to be had.

  She walked beside him, his hand resting lightly against her back. His car was parked a short distance down the road. When they reached it, he offered to drive her home. She knew she should refuse, but decided to let him do so anyway. The trip back to her apartment felt like it was an impossibly long distance to travel alone.

  “Are you sure you’re okay?” Kudo asked again as they got into the car. “If something has happened, don’t feel you need to hide it from me.”

  It’s no wonder he’s worried, she thought, with the way I must look right now. “No, I’m okay, really. I’m sorry.” She smiled at him, a performance that took all of her remaining strength.

  She was sorry, in so many ways. And it reminded her that Kudo had a reason for coming to meet her today.

  “Kudo—you said you had something important to discuss with me?”

  “Oh, that’s right.” He looked down. “Well, maybe today isn’t the best time.”

  “You sure?”

  “Yes.” He started the car.

  Yasuko let the motion of the vehicle rock her gently in her seat as she stared out the window. The sun had set. Night had come to the city. How easy it would be if everything went dark, and the world ended right here, right now. What a relief it would be.

  Kudo’s car stopped in front of Yasuko’s apartment building. “Rest up. I’ll call.”

  She nodded, and laid her hand on the door handle; but as she began to open the door Kudo blurted out, “Wait—”

  Yasuko turned back to look at him. He wet his lips and slapped his hands down on the steering wheel. “Maybe now is a good time, after all.” Kudo slid one hand into his suit pocket and pulled out a small blue jewelry case. Yasuko knew what it meant at a glance.

  “They have scenes like this all the time on those television shows, so it feels kind of cheesy now, but I suppose it’s the accepted ritual, so—” He opened the box in front of her. It held a ring. A large diamond caught the rays of the fading day and sent shimmers in every direction.

  “Kudo…” Yasuko’s mouth hung open; she stared amazedly into Kudo’s face.

  “Don’t feel you have to give me an answer right away,” he said. “There’re Misato’s feelings to consider, not to mention yours! I just want you to know that I’m not doing this on a whim. I know I can make you happy, both of you.” He took Yasuko’s hand and placed the box in it. “Take this, but don’t let it be a burden. This is just a present. If you should decide you would like to live with me, then the ring will mean what it is intended to mean. Please, think about it.”

  Feeling the weight of the small case in her hand, Yasuko’s mind went blank. She only heard half of what he was saying. Still she understood—which only fueled her confusion.

  “Sorry. I know it’s sudden.” Kudo grinned sheepishly. “You really don’t have to rush your response. I do want you to talk to Misato, too.” He reached out and closed the lid of the case in her hand. “There.”

  Yasuko couldn’t think of what to say. Words seemed almost inaccessible. There were too many images racing through her head. Pictures of Kudo, and Togashi, and Ishigami—mostly Ishigami.

  “I … I’ll think about it,” she managed at last.

  Kudo nodded, apparently satisfied. Yasuko smiled back and got out of the car.

  She watched as he drove off, then went up to her apartment. As she was opening the door, her eyes were inevitably drawn to the next door down the hall. The mail slot there was overflowing with letters, but there was no newspaper. Ishigami must have canceled his subscriptions before turning himself in. He had probably done it automatically, a common courtesy with no more significance for him then the act of waking up in the morning. She stepped inside.

  Misato wasn’t home yet. Yasuko sat and breathed a long ragged sigh. Then she got to her feet again and went into the back room. She took down a cookie box from a shelf there and removed the lid. The container held a collection of old letter
s. She lifted the entire bundle, removing one from the very bottom. Nothing was written on the envelope. It contained a single piece of ruled report paper, covered with writing.

  Ishigami had put the envelope in her apartment mailbox before making his final call on that last evening. In it she had found the note it still held, as well as three letters—all of them supposed proof of how he had been a stalker. She had surrendered the three letters to the police as evidence.

  The note told her how to use the letters, and what she should tell the detectives when they came to talk to her, all in Ishigami’s customary detail. There were instructions not only for Yasuko, but for Misato as well. It covered everything, every situation they might find themselves in, ensuring that no matter what befell the Hanaokas, they would know what to do. It was because of his instructions that Yasuko and Misato had been able to handle the police. Yasuko knew that if she made a misstep and the detectives saw through the deception, all of Ishigami’s hard work would go up in smoke. Misato must have known that, too.

  At the very end of his instructions he had added a final message:

  “I believe Kuniaki Kudo to be a loyal and trustworthy man. Marrying him will certainly increase the probability that you and Misato will be happy. Please forget about me. Feel no guilt. If you are not happy, all I have done will be for nothing.”

  She read the letter again and fresh tears began to flow.

  She had never encountered such deep devotion. She hadn’t even thought it existed. Yet Ishigami had it, hidden away beneath that expressionless mask of a face—the kind of passion unfathomable to the average person.

  When she heard that he had turned himself in, she had assumed that he was simply taking their place. But now that she’d heard the truth from Yukawa, the words Ishigami had left for her stabbed even deeper into her heart.

  She thought about going to the police and telling them everything. But that wouldn’t save Ishigami. He was a murderer, too, after all.

  Her eyes fell on the jewelry box Kudo had given her. She opened the lid and watched the ring sparkle.

  Maybe she should do what Ishigami wanted her to do—seize her chance at happiness. Maybe it was like he said: if she gave up now, all of his work would be for nothing.

  Still, it was so hard to hide the truth. Would she ever really be able to be happy, with something so dark hidden inside? She would have to live the rest of her life with this guilt, never knowing true peace. But maybe, Yasuko thought, enduring that guilt is a way of doing penance.

  She tried the ring on. The diamond was beautiful. How happy she would be if she could just run to Kudo, without a cloud in her heart! Yet that was a hopeless dream. Her conscience would never be clear.

  She was putting the box away when her cell phone rang. She peered at the LCD screen. The number was unfamiliar. She opened the phone.

  “Yes?”

  “Hello? Is this the mother of Misato Hanaoka?” It was a man’s voice that she didn’t recognize.

  “Yes. Is something wrong?” She felt her stomach flutter.

  “My name’s Sakano. I’m a teacher at Morishita Minami Middle School. Sorry for the sudden nature of my call.”

  “Is something wrong? Is Misato okay?”

  “Actually, she was just found behind the gymnasium. It appears that her wrists were cut with a knife or some other sharp object.”

  “What…?” Yasuko’s heart leapt into her throat and she gasped for breath.

  “She was bleeding badly, so they took her to the hospital immediately. Don’t worry, she’ll be fine. However, there is a chance that this was an attempted suicide. I thought you should know so you could take the necessary steps—”

  The man continued talking, but Yasuko didn’t hear a word he said.

  * * *

  A countless number of stains, scratches, and other small marks covered the wall in front of Ishigami. He chose several at random, and in his mind connected them all with straight lines. The resulting matrix was made up of triangles, squares, and hexagons. He began painting the shapes with four separate colors, not allowing any two adjacent shapes to share the same color. All of this he did in his head.

  Ishigami finished the problem in less than a minute. Wiping the image, he chose different spots and repeated the process. It was the essence of simplicity, yet he could do it over and over without losing interest. If he grew weary of the four-color problem, he decided he would just use the spots on the wall to define an analytical geometry problem. Calculating the coordinates of every spot on the wall would take a considerable amount of time.

  And that was just using the spots on the wall. Who cared if he wasn’t allowed to leave his room? As long as he had paper and something to write with, he could work on his math problems. Even if the authorities were to bind his hands and feet, he could explore new proofs in his head. They could take away his sight, or his hearing, but they could not touch his brain. Confinement was like a limitless garden of paradise for him. How short is a lifetime, he thought, compared to the time it will take humankind to find all the rich veins of mathematical ore where they lie sleeping and tease them forth into the world.

  Nor, he reflected, did he need anyone to acknowledge his work. Certainly he would have liked to publish his theories, to be recognized and reviewed; but that was not the true essence of mathematics. In academia it was always a race to see who would reach the summit of which particular mountain first, but as long as he knew which peaks he had discovered, that would be enough.

  It had taken Ishigami some time to reach this place. Not very long ago, he had been reduced to the terrible conclusion that his life had lost its meaning. If his only talent was for mathematics, he had reasoned, and yet he could make no progress along that path, what was the value of his existence? Every day, he’d contemplated death, feeling that if he died, no one would be sad, or really much inconvenienced. He doubted anyone would even notice.

  He remembered a certain day, only a year ago …

  He was standing in his apartment with a short length of thick rope in his hand. He was looking for a place on the ceiling to attach it. But he soon found that apartments lack any appropriate fixtures for hanging oneself. Finally, unable to find a better alternative, he resorted to pounding a large nail into a support post in the wall. He fixed his noose to it carefully and tested his weight on it. The post creaked alarmingly, but the nail did not bend and the rope did not break.

  He had no regrets. There would be no particular meaning to his death. Just like there had been no particular meaning to his life.

  He was standing on a stool, trying to fit his head through the noose, when the doorbell rang.

  It had to be fate.

  He only answered it because he didn’t want there to be any interruptions once he got started. Not knowing who was at the door, he had to consider that it might be an emergency. He couldn’t count on them just leaving him alone.

  He opened his door to find two women standing there—a mother and daughter, by the looks of them.

  The mother introduced herself, saying that they would be his neighbors. Her daughter bowed curtly beside her. When he laid his eyes upon them, a single realization pierced Ishigami’s entire being.

  How beautiful their eyes are, he thought. Until that moment, he had never been carried away by beauty of any kind. He didn’t even understand art. But in that moment, he understood everything. The very same beauty he found in unraveling a mathematics problem was standing right there before him.

  Ishigami didn’t remember clearly what the women had said. But the way their eyes had shifted as they looked at him, every blink of their eyelids, was burned into his memory.

  Ishigami’s life changed after he met the Hanaokas; in that moment he was renewed. All thought of suicide faded. Joy returned to his daily rituals. It made him happy just imagining where the two of them might be, what they might be doing. He had added the coordinates of Yasuko and Misato to the matrix of his life, and to him, it seemed like a miracle had occurre
d.

  Sunday was his happiest day. If he opened his window, he could hear the two of them talking. He couldn’t make out what they said, but the faint voices that drifted to him along the wind were like the sweetest music to Ishigami’s ears.

  He held no aspirations of ever being anything to them. He knew he should never even attempt to make contact. It was like his relationship with mathematics: it was enough merely to be associated with something so sublime. To seek any kind of acknowledgment would sully its dignity.

  Yet when trouble arrived and they needed help, it was only natural for Ishigami to go to their aid. After all, if they hadn’t been there for him, he would no longer be alive. He was returning the greatest of favors. They certainly had no idea what they had done, but that was okay. Sometimes, all you had to do was exist in order to be someone’s savior.

  When he saw Togashi’s body, Ishigami already had a program in his head ready to load. It would be difficult to completely dispose of the body. No matter how carefully he did so, he could never reduce the chances of discovery to a perfect zero. And even if he got lucky and succeeded in concealing what had happened, it would do nothing to ease the pain in Yasuko’s heart. She and her daughter would live in constant fear of discovery. He could not bear to visit such hardship on them.

  There was only one way to put Yasuko and her daughter truly at peace. He would have to detach them completely from the case. He would make it seem as though they were connected, and yet there could be no doubt that they had nothing to do with the murder.

  That was when he decided to use the Engineer—the homeless man who had so recently begun living at the camp near Shin-Ohashi Bridge. It all worked quite smoothly.

  In the early morning of March 10, Ishigami had approached the Engineer. He had found him sitting apart from the other homeless as usual.

  “I have a job for you,” Ishigami had told the man. He explained that he wanted him to help as an observer on a riverworks project that would last several days. He had noticed that the Engineer had a background in construction.

  The Engineer had been suspicious at first. “Why me?” he had asked.