After Natsuyu left, the building gradually returned to silence. The surroundings looked as though no one had been there for a very long time.
The sky slowly darkened, and the moon rose.
After some time, four children appeared at the location.
Just as in the original story, Conan relied on his intelligence and sharp reasoning to crack the code on the treasure map and pinpoint the treasure's location.
Standing directly beneath the treasure site, Conan spotted a single Maple Leaf Coin deliberately left behind by Natsuyu. He looked up—and sure enough, several bags were hanging from the ceiling. Those had to be the containers for the coins.
Genta and the others also noticed the coin on the ground.
"Ah! It's the treasure! We found it!"
Genta rushed forward excitedly, reaching down to pick up the coin.
But before he could touch it, a hand snatched it up first.
It belonged to a member of the Italian robbery gang. They had followed Conan and the others all the way here and discovered the treasure's location.
What followed unfolded just like in the anime.
Conan and the others were tied up. At this site, the Detective Boys carried out their very first coordinated operation. Working together, they cut the rope suspending the bags, causing them to fall and strike the three robbers.
Only this time, what knocked the criminals unconscious wasn't gold—but stones Natsuyu had placed in the bags before leaving.
Seeing their plan succeed, the four kids cheered in unison.
"We did it!"
But suddenly, Conan sensed something was wrong.
What spilled out of the bags weren't coins—but rocks.
That could only mean one thing: someone had taken the Maple Leaf Coins before they arrived.
However, this wasn't the time to dwell on where the coins had gone. The robbers could wake up at any moment, and with all of them still tied up, they were no match for grown criminals.
The top priority was to get to the police and report what happened.
Conan and the others rushed to the police station. Inspector Megure quickly arrived at the scene and arrested the three robbers.
This marked the Detective Boys' first official appearance, and Inspector Megure praised the children for their role in apprehending the criminals.
Unfortunately, despite a thorough search of the entire building afterward, the police failed to locate the stolen Maple Leaf Coins.
No one knew who had taken them—or how the stones had been swapped in their place.
To this day, the whereabouts of the Maple Leaf Coins remained a mystery.
On his way to school the next day, Conan kept thinking about what had happened.
He carefully reviewed the treasure map and his own reasoning process. He was confident that he had solved the code correctly—the Maple Leaf Coin on the floor and the bags hanging from the ceiling proved it.
So where had the coins gone?
Who had taken them—and how had they known where the treasure was?
Conan recalled the environment inside the building. When he and the others arrived, there were no signs that anyone else had been there recently.
Could the coins have been taken long before?
In truth, Conan had begun to suspect Natsume Natsuyu, whom he had coincidentally met the day before.
Aside from Genta and the others—and the robbers—only Natsuyu had seen the code on the treasure map.
Still, it felt unlikely.
Solving the code required observing neon lights at night. Conan had already solved it quickly, and he hadn't encountered Natsuyu along the way. There was no way she could have cracked the puzzle so soon after seeing it… right?
Even so, Conan couldn't completely dismiss the suspicion.
He decided that after school, he would return to the street where he'd met Natsuyu and see if he could find her again. Maybe he could test her subtly.
After school, Conan was eager to leave.
But Genta reacted faster and grabbed him.
"Conan, what's with you today? You've been totally out of it."
"Yeah," Mitsuhiko added. "We were calling you just now, and you didn't even hear us."
Ayumi looked worried. "Conan, is something wrong?"
"No, no—nothing," Conan said quickly. "There's just something I want to check."
Hearing this, Genta leaned in suspiciously.
"You're not trying to ditch the rest of the Detective Boys and handle something on your own, are you?"
"Definitely not," Conan replied, overwhelmed by their interrogation. Seeing that they wouldn't let it go, he finally said he wanted to look for Natsuyu, without mentioning his suspicions.
"Huh! That's not fair," Genta complained. "We want to see Sister Natsuyu again too!"
"Yeah," Ayumi agreed. "She left so fast yesterday—we don't even know where she lives."
At that, Genta, Mitsuhiko, and Ayumi exchanged a look and shouted together:
"Then the Detective Boys' second group activity begins now!
Objective—find Sister Natsuyu!"
With that, they charged ahead.
Conan sighed helplessly and followed.
When they reached the street from the day before, Genta and the others looked at the bustling crowd, unsure where to begin.
"So, Conan," Genta asked, "with this many people, where do we even start?"
Conan thought for a moment.
"We can ask the staff at nearby shops—especially cafés. Sister Natsuyu might have stopped to rest somewhere. She's pretty distinctive, and it hasn't been that long. Someone might remember her."
"Got it!"
Genta scanned the area and immediately spotted a café.
"There! Let's try that one!"
Before he even finished speaking, he dashed off.
Ayumi and Mitsuhiko followed close behind.
"…Sigh," Conan muttered, having no choice but to go after them.
Inside the café, Conan spotted a waitress who looked patient and approachable. He walked up to her.
"Um, miss, can I ask you something?"
Seeing a group of kids, the waitress crouched down and smiled warmly.
"Of course. What is it?"
"Did you see a very pretty lady here yesterday?" Conan asked.
"She was wearing yellow and white, with bright golden hair—very eye-catching."
"And her eyes were golden too," Ayumi added. "They looked like sunlight—really pretty."
Hearing the description, the waitress immediately thought of someone.
"Oh—you mean Natsume Natsuyu, right?"