Case 1 : The Mysterious Death in the Alley

opening scene : 

It was a an cool evening in the Paris, the streets dimly lit by amber streetlights. A faint drizzle pattered against the Pavelstones, pulled reflections of neon signs from the nearby cafes. Paul Beaumont, a well-known merchant, locked up his antique store, whistling an old tune as he prepared to head home.

The narrow alley behind the shop was eerily silent, save for the occasional drip of water from overhead gutters. Paul adjusted his coat, his breath fogging up in the cold night air. As he turned a corner , a shadow moved swiftly, too quickly to react.

A sign of metal. A muffled gasp. And Paul crumbled to the ground.

A person above him , a faint scuff mark appeared on the wall 2.5 meters high.

The shadowy figure in black darted away, their face was covered by black face mask and wide-brimmed hat. In the distance, a passerby screams upon discovering the body . Police cordoning off the area. Reporters swarm the scene, and one remarks, 

"THIS IS THE FOURTH MURDER LIKE THIS IN A MONTH " .

Detective Leaf ," one journalist pressed, " is there any update on this string of murders?"

Leaf sighed, visibly exhausted. We're investigating. That's all I can say for now."

Scene 1: Riku's Introduction to the case 

Riku Tanaka is visiting Paris with his baseball team. After practice, he strolls throughout the city, Soaking in the sights,thanks to an international baseball tournament. The sights were incredible, but what he truly enjoyed were the quiet moments, walking alone, absorbing the atmosphere.

 When he stumbles upon the crime scene. Curious, he stops to watch as the lead detective gives a vague statement to the reporters.

Riku's sharp eyes scanned the scene. The victim lay on the ground, one arm outstretched toward the alley wall. He noticed the faint scuff mark above.

His gaze shifted to the pavelstones, where he spotted a tiny metallic object glinting near the drain.

Unable to suppress his curiosity, Riku spoke up. "Detective, I think the scuff mark on the wall is important."

The detective turned, irritated. "Who are you?"

The detective leaf dismissed him, but an officer nearby recognized Riku from his reputation of being as a genius detective back home.

"Detective, this kid is sharp. He helped solve a theft case in Tokyo last year."

Detective leaf, then reluctantly allowed Riku to approach the scene.

Scene 2: Investigating the Scene:

Riku crouched beside the body, careful not to touch anything. He analyzed the scene meticulously.

By seeing the angle of the dagger embedded in Paul's chest was unusual-slightly upward, as if lunched rather than the thrust.

The metallic object in the drain was ball bearing. "This was no random attack,"Riku muttered. "The killer used physics."

He explained his theory to Lefevre. "The scuff mark on the wall? It's at the perfect height for a slingshot or catapult device. The ball bearing was likely part of the mechanism. The killer didn't even need to be here when Paul was attacked."

The detective leaf looked skeptical." Why go through such trouble?"

"To confuse the investigation," Riku replied. "This wasn't just a murder-it was staged to look like a spontaneous attack, but it's anything but."

Using a piece of chalk from his bag, Riku sketched the trajectory of the dagger on the ground. "The angle matches the height of the scuff mark. The killer must've positioned the device on the wall, set the trajectory, and activated it remotely."

By hearing this the detective leaf and the other officers and the reporters are shocked and one of the Paris reporters say that:

"Hey I know him he's the famous detective of Japan , He's non other than the famous high school detective RIKU THE GENIUS DETECTIVE ".

The reporter says like that.

Scene 3: The Suspects :

The investigation shifts to the identifying potential suspects. Three individuals were brought in for questioning:

1st suspect Emile : Pauls wife .

2nd suspect Amy : She is the apprentice of the paul .

3rd suspect Claude : Pauls business rival .

 1) Emile,Henri's estranged wife: Calm and composed, she claimed to have been at a dinner party with friends

 2)Amy,Henri's apprentice: A timid young women who claimed to be studying at home during the time of the murder

 3)Claude, Henri's business rival: Openly hostile toward Henri but insisted he had no reason to kill him.

Riku observed their body language closely.

Amy where she behaved differently like she avoided eye contact and had dirt under his nails, unusual for someone who claimed to be indoors .

 Emile fidgeted when asked about her alibi.

Claude seemed almost too confident, deflecting questions with arrogance.

Riku decided to dig deeper into their backgrounds.

Scene 4: The Twist :

 After hearing all these things and understanding the connection between the everything and creating assumptions in his mind like why would he kill him or his wife killed him for his property because she was partying when her husband was killed is she telling the truth or fake or his bussines rival claude he would be first person who would be benifited if the paul will die.

Riku revisits the crime scene with permission to recreate the crime. Using chalk and a physics diagram, he demonstrates how the killer used a slingshot-like device to hurl the dagger. The height of the scuff mark matches the launch angle needed for the dagger to hit Henri's chest.

He theorizes the killer used a string-based contraption tied to a street lamp. Riku demonstrates using basic materials, impressing the police.

A witness comes forward, mentioning they saw Amy near the alley earlier. But Riku isn't convinced. "It's too obvious," he says, "and this isn't just about physics—it's about motive."

Riku gathers everyone at the scene. He reveals his findings:

 1)Emile had motive—inheritance—but lacked the physical skill to use the contraption.

 2)Amy knew of Henri's schedule but didn't have access to the dagger.

 3)Claude, however, was skilled in mechanics (a past tinkerer) and had both the motive and tools to pull off the crime.The grease on the ball bearing matches the type used in your workshop. You had the knowledge, tools, and motive to carry this out."

 He builds tension on Claude about see you're the only person who would get benefited from his death .

Then Claude shouts and says "what are you saying and what proof do you have and first of all what do you think about his theify wife and that girl they also have reasons to kill the Paul man."

Then Riku stood before the gathered crowd of suspects, officers, and Detective Lefevre. The rain had slowed, but the air remained thick with tension. He adjusted his cap, his sharp eyes glinting under the dim streetlight.

"Now, let's put the pieces together," Riku began, his voice steady.

He pointed to the scuff mark on the wall. "This was the key. The killer planted a slingshot device here, rigged to launch the dagger with precision. The trajectory wasn't random—it was calculated, aimed directly at Mr. Beaumont. The ball bearing found near the drain acted as the trigger weight."

Riku glanced at Émile. "Émile, you knew Mr. Beaumont's routines, but the complexity of this device is beyond your skillset."

Émile stammered, "I-I don't even know what you're talking about!"

Next, Riku turned to Madame Beaumont. "Madame, you had every reason to despise your husband. Yet your alibi checks out, even if it's shaky. The precision of this mechanism suggests someone with a technical background."

The crowd murmured, eyes shifting uneasily toward Claude. Riku's gaze locked onto him like a hawk.

"And you, Claude," Riku said, taking a step closer. "Before you became a merchant, you were an engineer. The grease residue on the ball bearing matches the lubricant used in your workshop. It's a unique blend, isn't it?"

Claude's face twisted in anger. "That doesn't prove anything! Coincidence!"

Riku smirked. "The ball bearing? It's custom-made and serialized. I confirmed it with the manufacturer—this one belonged to a batch you ordered last year for a prototype device."

Claude's defiant facade began to crack.

Here's a revised and extended version of your scene, adding a tension-filled twist where a rooftop shooter intensifies the drama, similar to Detective Conan's style.

Scene: The Climax of the Crime Reconstruction

Riku stood before the gathered crowd of suspects, officers, and Detective Lefevre. The rain had slowed, but the air remained thick with tension. He adjusted his cap, his sharp eyes glinting under the dim streetlight.

"Now, let's put the pieces together," Riku began, his voice steady.

He pointed to the scuff mark on the wall. "This was the key. The killer planted a slingshot device here, rigged to launch the dagger with precision. The trajectory wasn't random—it was calculated, aimed directly at Mr. Beaumont. The ball bearing found near the drain acted as the trigger weight."

Riku glanced at Émile. "Émile, you knew Mr. Beaumont's routines, but the complexity of this device is beyond your skillset."

Émile stammered, "I-I don't even know what you're talking about!"

Next, Riku turned to Madame Beaumont. "Madame, you had every reason to despise your husband. Yet your alibi checks out, even if it's shaky. The precision of this mechanism suggests someone with a technical background."

The crowd murmured, eyes shifting uneasily toward Claude. Riku's gaze locked onto him like a hawk.

"And you, Claude," Riku said, taking a step closer. "Before you became a merchant, you were an engineer. The grease residue on the ball bearing matches the lubricant used in your workshop. It's a unique blend, isn't it?"

Claude's face twisted in anger. "That doesn't prove anything! Coincidence!"

Riku smirked. "The ball bearing? It's custom-made and serialized. I confirmed it with the manufacturer—this one belonged to a batch you ordered last year for a prototype device."

Claude's defiant facade began to crack.

The Rooftop Twist :

Just as Riku prepared to deliver the final blow, a faint metallic click echoed from above. Everyone froze.

"Don't move!" a deep voice commanded.

All heads tilted upward to see a shadowy figure perched on the rooftop, silhouetted against the night sky. The figure held a pistol, its barrel gleaming under the pale moonlight, aimed directly at Claude.

"Claude," the voice barked, "you've betrayed us for the last time!"

The tension was electric. The officers reached for their weapons, but Riku raised a hand. "Wait!"

Riku's mind raced. He scanned the rooftop and noticed a faint glint behind the shooter—a loose gutter pipe, hanging precariously. The angle was perfect.

"Claude is a coward!" Riku shouted suddenly, his voice sharp and deliberate. "If he was brave enough to defy you, he wouldn't have gone through all this trouble to hide his crime!"

The shooter hesitated, their aim wavering. That was all Riku needed. With a quick flick of his wrist, he threw his baseball into the air. It ricocheted off the nearby lamppost and struck the loose gutter pipe, dislodging it.

The pipe crashed onto the shooter, knocking the gun from their hands. Officers swarmed in, scaling the building and apprehending the figure.

The Final Revelation

The rooftop assailant was revealed to be Jacques, a rival merchant with ties to Claude. Jacques had discovered Claude's plan to murder Paul and wanted to silence him before he could confess.

Riku pieced it all together. "Jacques knew about the slingshot device because he helped Claude design it. But when Henri became the target instead of Jacques' preferred victim, Jacques felt betrayed."

Claude, now pale and trembling, broke down completely. "It was supposed to be Jacques! Paul got in the way—he was never the target!"

Ending Scene

As both culprits were taken into custody, the rain began again, gentle and cleansing. Riku stood beside Leaf, watching as the alley emptied.

"You've got nerves of steel," Leaf remarked, lighting a cigarette.

Riku chuckled, spinning his baseball in his hand. "Sometimes, all you need is the right angle and the right moment."

And the reporters were amazed by his intelligence and tries to get an interview and then our Riku runaway from the interviews but the interviewers take an photo of him in running and in the next day we see that in Paris that in every news channel that a new high school detective from japan has solved an case .