Chapter 21 Section 13

Kusanagi pressed the disposable lighter several times before finally lighting the cigarette.There was a little wind, but not enough to shake the corners of the coat. "You were warned 'no fireworks'." Kaoru reminded him. "He means the vicinity of the device, right? I know it." Kusanagi let out a breath of smoke and cast his gaze into the distance. A shelf that looked like an arrow tower was set up in the grass, and the people from the forensic department were working around it seriously, while Yu Chuan and Dao were standing beside the shelf and talking about something.

"Kusanagi," Yukawa called to him, "Hey, I saw it." "What annoyance!" Kusanagi frowned, and extinguished the cigarette in the ashtray he carried with him. Seeing Yukawa waving in this direction, Kaoru walked over with Kusanagi. "have a look at this." Yukawa handed Kusanagi a square box about ten centimeters long, with a thin heart-shaped metal plate embedded in the center of the box. "What's this?" Kusanagi asked. "The metal plate is made of stainless steel and is about a millimeter thick, but it is not uniform. Why it is made like this, I will explain later. The back of the metal plate is coated with a gel-like explosive, and the back of the explosive equipped with a radio-controlled detonator."

"This thing is really dangerous enough." "That's why I told you that smoking is strictly prohibited. Sorry, please don't smoke here." Kusanagi curled his lips and raised his one-sided eyebrow. "Imagine this shelf is the bookshelf in the Tomonaga Fubetsu House. From the plan view, there is a window about five meters away from here." A model of a glass window stood where Yu Chuan pointed. Behind the window was a small bag of earth; in front of the glass window was a table with a square object wrapped in cloth. "what is that?" Hearing Kusanagi's question, Dao replied, "It's pork."

"That's for testing penetration, because we can't use people as tests." "I see." Yukawa placed the box in the center of the shelf, and carefully adjusted the position with the side with the metal plate facing the glass window. "This way all the preparations are over, stay away." Hearing Yu Chuan's words, Da Dao announced that everyone retreated.Kaoru followed Yukawa and Kusanagi to hide behind the car parked 20 meters away. After a few conversations with his companions on the walkie-talkie, Dao told Tang Chuan: "You can start at any time."

"Okay, let's do it." Tang Chuan glanced at his watch and began to operate the laptop. Everyone first heard a muffled sound, followed by the sound of glass shattering. "The experiment is over." Tang Chuan said. After Daichi and Kusanagi followed Yukawa out of the car, Kaoru hurried to catch up. Yu Chuan, who was walking in the front, bent down to pick up the piece of cloth holding the pork, and the cloth was blown off the table.He untied the cloth and handed it to Xun and the others: "Let's have a look." Kaoru's eyes widened: I saw a hole in the thick pork that seemed to be cut by a sharp instrument, and this hole penetrated the other side of the meat.

"It's like being stabbed with a knife." Kusanagi expressed Kaoru's thoughts, "Where did the blade disappear?" "Over there." Tang Chuan pointed to the soil bag. Not long after, a member of the forensic department investigating the soil bag picked up something and shouted: "Found it!" The things were immediately handed over to Tang Chuan. "Pretty." Tang Chuan said in a low voice after taking the thing. Kusanagi widened his eyes. "That heart-shaped metal plate turned out like this? It's unbelievable!" Kaoru felt the same way.That piece of metal had completely turned into the shape of the tip of a knife. Although it couldn't be said to be extremely sharp, it was so sharp that it could poke into the flesh with a little force.If you look closely, a hollow has formed inside.

"What's going on here? You can explain it to us laymen in an easy-to-understand manner." Kusanagi said. In the presence of Mamiya and the head of the forensic department, Yu Chuan explained the previous experiment in a conference room of the Metropolitan Police Department. "Normally, the force that causes an explosive to explode spreads in a spherical shape. It may be easier to understand it as 'in all directions'. But through various treatments of explosives, we can limit the direction of its diffusion. For example, in the explosive If a conical depression is made on the block, the energy of the explosion will be concentrated in front of the depression. This phenomenon is called the "Monroe effect". Or stack more than two kinds of explosives in layers, so that more than half of the explosion energy can be concentrated in the direction you want. If these processed explosives are covered with metal plates, then the metal plates will be affected by the energy of the explosion. The reaction force is blown away, and the deformation is produced at the same time. The important thing is that we can also control the deformation. If we make a depression in the center of the circular metal plate, the energy of the explosion will first reach its center, and the result , the center part of the circle will fly out first, and the rest will fly out the farther away from the center."

Tang Chuan took out a handkerchief from his arms and handed it to Xun beside him, saying, "Help me tighten it with both hands." After Kaoru pulled it out according to his words, Yu Chuan stretched out his index finger and pressed the center of the handkerchief. "In the end, the tip will protrude and deform like this. Judging from this shape, the blown metal has extremely strong penetrating power. In fact, people have indeed used this principle to create a weapon called ' Self-destructing fragments'. Of course, there are also peaceful methods of utilization, and the method of forming metals using this principle is called 'explosive forming' or 'explosive processing'."

Yu Chuan took out a document from the bag beside him, it was the one that Kaoru had seen before. "This is a paper written by Mr. Yukina Yukina about 20 years ago. The title is "Analysis of the Fluidity of Metals in Explosive Forming". Through a large number of experiments, Tomonaga clearly listed how the metal will be deformed by the explosion. Explosives The type, quantity, shape, material, shape, and size of the metal plate—he has tried countless combinations, and finally achieved a near-perfect simulation success. That teacher...Tomonaga-sensei, as long as metal Once in his hands, he can make it change shape at will. In honor of his technical prowess, we honor him as the 'Metal Magician'."

He turned to a certain page of the information and pointed it out to everyone present. "Here is his simulation experiment at that time. This time, according to the plan above, I found a condition that can make the shape of the metal resemble the tip of a Japanese sword. The experiment just now was based on this. As for other As a result, it was just like what Detective Kusanagi, Detective Utsumi, and everyone in the forensic department saw." Speaking of this, Yu Chuan sat down on the folding chair as if he had let out his last breath. "I see." Mamiya fiddled with the deformed metal piece with his fingertips, "But is it that easy to install this kind of device? It doesn't seem easy to determine the location."

"As you said, on the day of the incident, Mr. Youyong went to the other house. Although it was only a few minutes, he was alone. It is estimated that he set the position at that time. I guess he probably It is to disguise the device as a book. As for the important factors, height and angle of setting, he actually has a special tool for positioning." "tool?" "That's the cane. He modified the cane into a retractable one. If he wants to hit the victim's body accurately, the usual length is not enough. In addition, he also installed a laser pointer on the handle. I guess he used it to calculate the flight position of the emitted metal." Mamiya shook her head.Comparing does not mean incomprehension, but to express amazement at Yu Chuan's unique insight. "But he's doing remote control, right? How can he make sure the metal hits the victim?" After hearing this, Kusanagi interjected, "Then let the victim stand on the flight track." "How to do?" "Use the phone. Although NTT did not leave a record of using the phone at that time. Their home has an intercom connecting the main house and other houses. He can call the victim to stand by the window." "Just ask the victim to stand by the window? Isn't he afraid that the victim will become suspicious?" "Speaking like this will indeed make the victim suspicious. So, for example, he can say that someone is going to drag your precious kayak away. Yukina Yukiko told the victim beforehand that the people in the town association hoped that their family would The kayak can be put away, but according to our investigation, this is not true, and this is probably the foreshadowing he planted for this call. The victim naturally walked to the window after hearing this Go and see your kayak. And Tomomaga can clearly see the windows of other houses from the window, he only needs to confirm that the victim is standing by the window and press the detonator." After talking eloquently, Kusanagi turned to look at Yukawa and smiled slightly.This reasoning is wonderful, but unfortunately Kusanagi did not come up with it himself. Mamiya pondered: "So have you consulted the doctor in charge of the autopsy?" "I have consulted." Kaoru replied, "The doctor thinks that the possibility of the head being pierced by a sharp instrument of this shape is very high, that is, if it can be done." Gamiya folded his hands: "Then there is no doubt about it. The next step is the issue of evidence." "Just find the murder weapon that broke through the window glass." Kusanagi said, "It probably sank to the bottom of the water." "Then ask someone to fish for it." Jian Gong slapped the table and stood up. Everyone walked out of the room one after another, and when Xun was about to leave, she suddenly thought of something and turned to look behind her, only to see Tang Chuan still sitting on the chair, staring blankly at the document. "Teacher Tang Chuan," she called him, and asked Tang Chuan who raised his head to look at her, "Is this okay?" "Of course, is there a problem?" "No." Kaoru shook his head, walked out of the room, and Kusanagi was waiting outside the door. "That guy is a real scientist, so he can't forgive someone who uses scientific knowledge to kill someone, even if the other person is his teacher." Kaoru nodded silently.