His wife pulled out a comforter from the closet and placed it over him. His complexion was sallow with fatigue. She awakened him shortly after he had fallen asleep.
“It’s ten o’clock already.” Yoshiko sat beside him, looking at him in sympathy.
“Is it?” Imanishi flung off the comforter and got up.
“Aren’t you still sleepy?”
“No, sleeping even that little bit helped a lot.”
Imanishi washed his face with cold water. He felt much better.
“You’ll be home early tonight, I hope?” his wife asked as they ate breakfast.
“Yes, I’ll come home early tonight.”
“Please do. Otherwise, you’ll come down with something.”
“You’re right. I used to be able to spend two nights in a row without sleep on a stakeout without feeling tired.” He was getting on, there was no denying it.
He reached headquarters after eleven and reported to the section chief.
Imanishi next went to the Kamata police station to see Yoshimura and bring him up to date on his findings. Yoshimura listened intently, eager to catch every word.
“That ends the part about Kyoto,” Imanishi said. “Now it’s time for Tokyo. Since we last met I’ve learned something about acoustics.”
“Acoustics?”
“The study of sound.” Imanishi described what he had learned.
“Oh, I see.”
“Next, it’s this,” Imanishi said, leafing through his notebook. “Look at this.”
Yoshimura looked at the piece of paper he had picked up near the spot where Miyata had died.
“Do you think this has anything to do with Miyata’s death?”
“I thought at the time that someone must have dropped it there by accident, but now I think it was dropped intentionally.”
“What do you mean, intentionally?”
“It can be viewed as a challenge by the person who put it there.”
“A challenge?”
“When people become arrogant, they feel like sneering at others, certain that they won’t catch on. That’s what I think this represents.”
“But this is a listing of distributed insurance amounts.”
“Yes, it is. There’s no mistaking that. I suspected these figures, so I had them checked out. I didn’t think there was any reason to write down patently false figures, but I had it checked out just to be sure. These are the actual figures.”
“What’s the relationship between these numbers and Miyata’s death, then?”
“Look at it carefully. There are parts where no monetary amounts are filled in. See, under 1953,1954, and 1955. From 1949 on none of the years have figures, while there are two lines between 1953 and 1954. Even if the years before 1952 were omitted, why are there two lines between 1953 and 1954?”
“I can’t figure it out.”
“I thought initially that there was some statistical reason for this. But when I thought carefully about it, it seemed odd. There’s no reason to leave blank spaces like this.”
“Do you think there’s a particular meaning to the blank spaces, as well?” Yoshimura asked.
“I think so. The blanks between 1953 and 1954 make it look as though there were no further disbursements during that time, that there wasn’t a second, or a third, payment during that year. But just the opposite occurred. These lines were placed without any meaning when you look at this as a statistical table.”
“I don’t think I’m following you,” Yoshimura said, resting his chin in his hand.
“The amounts of unemployment insurance disbursed are noted as 25,404 and 35,522. If you read these numbers in the normal way, you would read them as twenty-five thousand four hundred four and thirty-five thousand five hundred twenty-two. I just told you what I heard about acoustics, right?”
“Yes.”
“In simple terms, the human ear can’t hear sounds that are too low or too high. In ordinary cases, sounds over twenty thousand cycles can’t be taken in as sounds by people…”
“Oh, I get it. These numbers of 25,000, 30,000, 24,000, 27,000, and 28,000 could signify high-frequency cycles,” Yoshi-mura said.
“Exactly. They’re ultrasonic waves. This table of insurance distribution is also a table of suggested distribution of ultrasonic frequencies.”
“Then do the blank spaces signify rests, the kind they often have in music? I think they call them pauses.”
Imanishi was totally ignorant about music. “I think that must be it.”
“So the high-frequency sounds were not to be emitted continuously, but there were to be pauses in between. If you followed the table that’s what would happen,” Yoshimura said.
“That’s how I interpret it. The high-frequency sound wasn’t continuously transmitted. By putting the pauses in, the frequency would change as noted in the table.”
Yoshimura’s expression showed his admiration for Imanishi’s deductions.
“It would probably have a greater effect on someone to have slight frequency changes rather than a continuous emission of the same frequency sound wave.” This was not Imanishi’s own opinion, but based on information that he had heard from Hamanaka. “I think that these pauses weren’t complete rests and that there was some kind of sound during these pauses as well.”
“So it wasn’t a complete blank during the pause?”
“No, it wasn’t. The sound continued, but it became a pleasant sound.”
“Pleasant sound? You mean music?”
“Yes, exactly. Between the different ultrasonic waves, music was played.”
Imanishi went on, “Assume that Miyata and Emiko were murdered using these ultrasonic waves. This is a new method of committing murder, one that we haven’t seen before. But we have to consider something here. Just suppose… this is just a supposition… if the person who killed Miyata and Emiko is the same as the one who killed Miki at the Kamata railroad yard, you notice a big difference in the style of the murders.”
Yoshimura nodded. “There’s a huge difference. That murder was by strangulation, and then the victim’s face was battered with a stone. You can’t get much more violent.”
“That’s right. That method of murder was simple and brutal. We could also say that it was spontaneous. In other words, it was not planned. If Miyata’s and Emiko’s deaths were murders, however, the murderer used his cunning and killed them after intricate planning. Isn’t there a contradiction in this? If these crimes were committed by the same murderer, how do we explain this?”
“Let me see.” After some thought, Yoshimura said, “Could it be because Miki arrived in Tokyo unexpectedly?”
“That’s exactly what I think. Miki arrived in Tokyo early on the morning of May eleventh,” Imanishi said. “He was killed between midnight and one a.m. the night of the very same day he arrived in Tokyo.”
“Yes, that’s true.”
“Miki had a reason for coming to Tokyo. And his movements from the morning until the night of the eleventh are what caused him to be killed.”
The two men were silent for a while, each thinking his own thoughts.
“At any rate,” Yoshimura said, breaking the silence first, “the murderer wasn’t yet prepared to kill Miki ultrasonically.”
“That’s what I think. That’s why we need to find out if the murderer procured the needed equipment between May 11 and August 31, when Miyata was killed. I think that will be one of the conclusive pieces of evidence.”
“But wouldn’t the procurement of equipment have been carried out in strict secrecy?”
“That may be so, but he seems to be convinced that no one can figure it out, that he is too clever to be caught. Even if he made his preparations in secret, I think there must be some place he was careless. That’s why we must look.”
Yoshimura’s gaze fastened on Imanishi’s face.
“Imanishi-
