The Devotion of Suspect X - Keigo Higashino [30]
However, it was true that events were developing according to plan. He had known they would find out eventually that Togashi had been looking for Yasuko—that was why Ishigami had made the effort to establish an alibi. He had also expected the police to question that alibi.
And he had expected that the police would try to make contact with Misato. They must have hoped she would be the weak link in the chain, a way to take apart the alibi in the absence of any witnesses. Ishigami had taken several steps to prevent that from happening, but he thought now that it would behoove him to check once more and make sure he hadn’t overlooked anything.
Ishigami returned to his apartment, his mind racing, only to find a man standing in front of his door—a tall fellow, unfamiliar, wearing a thin, black jacket. He must have heard Ishigami coming up the steps, for he was facing toward him. His wire-rim glasses glittered.
At first, Ishigami thought it was another detective. But then he realized that no, that was wrong. The man’s shoes were in perfect condition, as good as brand-new.
He approached, warily, and the man spoke. “Ishigami?”
Ishigami looked up at the stranger’s face. The man was smiling. It was a smile he remembered.
Ishigami took a deep breath, and his eyes went wide as the memories came vividly back to him from a twenty-year distance.
“Manabu Yukawa.”
SIX
The classroom felt deserted that day, as always. The room was large enough to seat a hundred students, but there were only twenty or so there now. Most of them were in the back row so that they could slip out after attendance had been taken or work on some project of their own during the lecture.
Very few undergraduates wanted to be mathematicians. In fact, Ishigami was probably the only one in his entire class. And this course, with its lectures on the historical background of applied physics, was not a popular one.
Even Ishigami wasn’t all that interested in the lectures, but he sat in the second chair from the left edge in the front row. He always sat there, or in the closest available position, in every room, at every lecture. He avoided sitting in the middle because he thought it would help him maintain objectivity. Even the most brilliant professor could sometimes err and say something inaccurate, after all.
It was usually lonely at the front of the classroom, but on this particular day someone was sitting in the seat directly behind him. Ishigami wasn’t paying his visitor any attention. He had important things to do before the lecturer arrived. He took out his notebook and began scribbling formulas.
“Ah, an adherent of Erdős, I see,” said a voice from behind.
At first, Ishigami didn’t realize the comment was directed at him. But after a moment the words sank in and his attention lifted from his work—not because he wanted to start a conversation, but out of excitement at hearing someone other than himself mention the name “Erdős.” He looked around.
It was a fellow student, a young man with shoulder-length hair, cheek propped up on one hand, his shirt hanging open at the neck. Ishigami had seen him around. He was a physics major, but beyond that, Ishigami knew nothing about him.
Surely he can’t be the one who spoke, Ishigami was thinking, when the long-haired student, still propping up one cheek, remarked, “I’m afraid you’re going to hit your limits working with just a pencil and paper—of course, you’re welcome to try. Might get something out of it.”
Ishigami was surprised that his voice was the same one he’d heard a moment earlier. “You know what I’m doing?”
“Sorry—I just happened to glance over your shoulder. I didn’t mean to pry,” the other replied, pointing at Ishigami’s desk.
Ishigami’s eyes went back to his notebook. He had written out some formulas, but it was only a part of the whole, the beginnings of a solution. If this guy knew what he was doing just from this, then he must have worked on the problem himself.
“You’ve worked on this, too?” Ishigami