The pond was two meters deep and surrounded by a tall railing. A small gate opened into a clearing a few meters wide—the designated fishing spot where Heiji and the others were standing.
All eyes were on the water.
Soon, the diver resurfaced and shook his head at Inspector Yokomizo.
"Inspector, there's nothing at the bottom of the pond."
"What? Impossible!" the inspector exclaimed. "Are you sure you looked carefully?"
"Are there any rocks or anything like that?" Heiji asked, frowning.
"No, there's nothing. Not even a small pebble, let alone a large rock."
The scene fell silent.
"It seems the great detective's reasoning has run into a problem," Yokota Jousaku sneered.
"What are you laughing at?" Yoko Okino shot back, glaring at him. "With that kind of smile, maybe you're the killer."
Heiji glanced at Yoko. It seemed an idol's public image and private personality could be very different.
"Inspector, if there's nothing else, I'm leaving," Ueno Yokohama said coldly. "I've wasted too much time today."
"Please wait a moment," Inspector Yokomizo pleaded. "If we really don't find anything, I'll let you go."
Heiji watched Ueno, thinking. He's the killer. I'm sure of it. But what's the weapon? There's nothing around here to use… except for that stool.
A stool?
Heiji walked over to the chair where President Nohara had been sitting. He picked it up and examined it.
"Mr. Heiji, did you find something?" the inspector asked hopefully.
Heiji set the chair down and shook his head. Too small. And the weapon should be relatively large. Where could he hide something like that? Could it be… in plain sight?
He almost laughed at the thought.
In plain sight…?
Suddenly, an idea struck him. He whipped his head around toward the pond.
That's it. I get it now. So it was that kind of weapon. An adventure journalist, indeed.
A confident smile spread across Heiji's face. He knew what the murder weapon was.
"Inspector, I've been delayed long enough," Ueno said angrily. "If you keep detaining me, I don't mind suing you."
"You're in a hurry to leave, Mr. Ueno," Heiji said suddenly. "Are you afraid of something?"
Ueno glanced at him with disdain. "I admit you've foiled thieves like the Night Baron and Kaitou Kid, Mr. Hattori. But so much for your reputation…"
He shook his head dismissively.
"Watch your mouth," Yoko snapped. "Heiji knows what he's doing."
Heiji simply smiled. "Mr. Ueno, as an adventure journalist, you must have been to a lot of places, right?"
Ueno's expression tightened. "What are you getting at?"
"I remember you saying you've been to volcanic craters and glaciers, correct?"
"That's right," Ueno said, his face unreadable. "I've also been to the Amazon River and the Egyptian pyramids. I've seen most of the world's famous sites."
"Then you must have brought back souvenirs. Like a piece of a pyramid… or perhaps, a pumice stone."
Ueno's face went pale. He stared at Heiji, alarmed, his hand reflexively adjusting his glasses.
"You must be joking, Mr. Hattori. A piece of a pyramid has no collection value."
The others watched, completely lost.
"True," Heiji agreed. "But pumice does. After visiting a volcano, you probably brought a piece or two back, didn't you?"
Seeing sweat appear on Ueno's forehead, Heiji's smile widened.
"What's pumice?" Yoko asked, voicing what everyone was thinking.
"Pumice is a porous, lightweight volcanic rock," Heiji explained. "Its key feature is that it can float on water—and from a distance, it can look like something harmless on the surface."
"Float?" Inspector Yokomizo snapped his head toward the objects drifting on the pond. "Quick—get those out and examine them!"
Soon, the results came back.
"Inspector, the lab confirmed it… it's pumice."
The inspector's expression hardened. "Mr. Ueno, do you have anything to say?"
"Wait," Ueno said, forcing himself calm. "On what grounds are you arresting me?"
The inspector hesitated and looked at Heiji.
"You have no evidence that I attacked President Nohara," Ueno sneered.
"You wrapped the pumice, tied it to the hook of your fishing rod, and cast it from over by the flowerbeds," Heiji said, his voice steady.
"It struck President Nohara in the head. When he staggered up, you swung the line again, hit him from behind, and knocked him into the pond."
"Then, when you ran over to 'help,' you simply reeled in the line and tossed the pumice fragments into the water."
"A clean trick," Heiji finished. "Who would suspect the murder weapon was floating on the surface the whole time?"
Silence.
Everyone stared, stunned.
"Inspector, check Mr. Ueno's hook," Heiji said. "It should be bent."
The inspector grabbed the fishing rod. His expression changed immediately. "It is. The hook is bent."
"That's from the weight of the stone," Heiji said.
"Lies!" Ueno shouted. "My hook bent last week when it got caught on trash underwater! I forgot to replace it. That proves nothing!"
"Mr. Ueno," Heiji said calmly, "on such a hot day, why are you wearing that thick towel around your head? Was it the same one you used to wrap the pumice, so it wouldn't shatter on impact?"
Ueno stopped shouting. He stared at Heiji, defeated.
After a long moment, he lowered his head. "How did you think of pumice, Mr. Hattori? It's not common."
"Your method was simple and nearly perfect," Heiji said. "But sometimes, perfection itself is the problem."
"Is that so…?" Ueno exhaled. "As expected. I confess."
Heiji stood with his hands in his pockets, looking at the pumice fragments drifting on the pond, completely sure of himself.
Yoko watched him closely, impressed.