"Investigation? What do you mean, man? Those matters are for the police, not us. You don't have to worry too much about my cousin."

"I'm not concerned about your cousin. This has something to do with those things, Wendy. The...anomalies."

"Anomalies...? Wait, so...is it a ghost? or some monster?"

"It...has something to do with something like that. I don't know precisely what it is."

We headed to the Mystery Shack, as we needed a ride. I wasn't well-versed in driving a car, but a golf cart posed no challenge. However, before I could take the wheel, Wendy claimed the driver's seat.

"Let me drive. I'm a pro at handling this thing."

"...Sure. First, we should head to the post office."

"Post office? Ah, right. We're going to track the person who sent you my moisturizer, right?"

"Yes."

Wendy drove with remarkable ease, much better than I could ever manage. It didn't take long for us to reach the post office.

We disembarked from the cart and entered the establishment. It was remarkably tranquil, with only one office worker idly gazing at his computer monitor. He looked at us with surprise.

"Oh, how can I help you folks?"

"We need access to the CCTV. Someone sent this package from this post office, as per the address. We need to ascertain the sender's identity and the transaction date."

The post office worker scrutinized the package, and then had a realization.

"Ah! This is...Um, I'm not really supposed to share this according to the work rules... But I'm feeling a bit bored, so why not? I observed the person sending this specific small package on... I think, Tuesday."

He then presented us with CCTV footage. A slim, tall figure was clad in a long coat, a hat, sunglasses, and a mask. The person meticulously packed the moisturizer and handed it to the worker.

"...Who is that weirdo?" Wendy seemed repulsed. But then...

The individual turned to face the CCTV camera. First, they removed their hat. Then the coat. Subsequently, they removed their sunglasses and mask, revealing themselves. Their distinctive fiery red hair was impossible to overlook.

Neither Wendy nor I could find words to utter.

The person who sent the moisturizer was Wendy herself, and she held a small nail gun.

"Wait, wait, wait... Wendy, is there any chance you did this unconsciously? Like, under someone's control or something?"

"Hey, what were you doing on Tuesday at this time?"

Wendy's tone carried frustration. Right, I remembered.

"We were working together..."

"Yes, so it's physically impossible for me to be in two places at once. And I distinctly remember that my cousin's woodworking shop was robbed... on That day. And that's the nail gun that his shop had. I suppose there's someone in Gravity Falls who looks exactly like me."

Wendy clenched her mouth and stared at the footage once again. Then, she opened her mouth.

"If... I can't prove my innocence or alibi, the police will eventually find out that... That thing is the criminal, and they'll suspect me. Ray... We have to do something!"

"...Okay. Calm down. We're going to catch that thing. Let's head back to the cart."

We rushed to the cart and sat in silence for a while.

I quickly reviewed my thoughts. Come to think of it, I'd researched a horror story similar to this one. Actually, it's quite well-known...

"Wendy, do you know that these... anomalies are usually based on horror stories or urban legends?"

"...No."

"I think I know what this story is. I researched these since I had to...encounter them quite often..."


[Doppelgänger]

It's an urban legend/myth that originated in Germany.

March 8th, 1808. Goethe, the famous author known for his works like 'Faust', was riding alone through the forest. He suddenly saw someone who looked exactly like him, riding the same horse he was on, on the other side of the forest. Astonished, Goethe tried to find the man again, but he vanished inexplicably.

Ryunosuke Akutagawa, a Japanese writer famous for works like 'In the Woods,' told his friends that he saw someone who looked exactly like him before he passed away. According to him, there were manuscripts on the table that he hadn't written, and even situations where a person identical to him had drinks with his friends. Not long after, he took his own life.

July 8th, 1822. Percy Bysshe Shelley, a Romanticist poet from England, told his wife that he'd seen a person who looked just like him while taking a stroll around the house. His wife didn't believe him, but later, when her husband went yachting, her neighbor Mrs. Williams told her that her husband had just walked by. Startled, she waited at home for her husband's return, but he was found dead in the sea.

In 1612, John Donne, a metaphysical poet from England, was having dinner in Paris when he witnessed his wife carrying a baby past him not once, but twice. That night, his pregnant wife had a miscarriage.

"...So, we call the person who looks identical to us a doppelgänger. According to stories, if you try to find them, they vanish within sight. And in modern times, there are stories that if you try to film them with a camera or other devices, they fail to work at that exact moment. The person who has a doppelgänger dies within days of encountering them."

"So...that thing is my doppelgänger. That's what you're trying to say, right?"

"Yes, Wendy."

Wendy pressed her fingers to her forehead, deep in thought.

"...And, my doppelganger probably tried to rob my cousin's place to make me a criminal?"

"Well, for now, it seems like it."

"So, what can we do?" Wendy asked me. "I can't face it; I'll die if I see the doppelganger."

"Well, I can. It probably won't matter to me. Do you have a weapon or something?"

"I have a nail gun...which is my dad's, not the one from my cousin's! I carry it just for self defense."

I eyed the nail gun suspiciously, but Wendy assured me it was her father's, not the doppelganger's. The nail gun, small and yellow, looked similar to the one the doppelganger had used to kill me. However, I couldn't draw a definite conclusion, as it might be a common brand.

"...In any case, our immediate goal is to track down that doppelganger."

Without warning, Wendy took the wheel and drove off. I quickly fastened my seatbelt.

"Wendy? Where are we going?"

"To the mayor's office. I found out that we can check the town's CCTV footage there."

It sounded like a solid plan, so I went along with it. In no time, we arrived at the mayor's office, and Wendy hopped out of the cart.

"Ray, dude, stay here. I know a guy working here, so I can get some help from him. But we shouldn't attract too much attention by having too many people entering the place at once."

"Fair enough."

Wendy disappeared into the office, leaving me with time to think. I couldn't shake the feeling that the doppelganger might be connected to the eavesdropper in my room. But why would someone go to such lengths to install it? I had to set that question aside for now and focus on the matter at hand: Wendy's doppelganger.

To summarize, there were two main possibilities. First, Wendy was herself, which didn't explain how she appeared in my locked room without a trace. This scenario suggested she might be running from her doppelganger and seeking my help. However, it didn't account for how she knew about my time loops and why she hadn't warned me about the doppelganger.

The second possibility was that the Wendy I had been with was the doppelganger, impersonating the real Wendy. This option explained her ability to appear and disappear, matching typical doppelganger behavior. Still, it didn't clarify how she was aware of my time regressions and why she hadn't instructed me to find her.

...I wasn't entirely sure which scenario was accurate, but one thing was clear.

If I stayed passive, the police would eventually unearth Wendy's doppelganger, leading to chaos at the Mystery Shack and a disruption in the original storyline. It was clear that the person behind these enigmatic items was extremely cunning and malevolent, actively probing for a weakness in my abilities.

'Bill...'

He was back, and he meant business.

Suddenly, someone sprinted towards the cart. It was Wendy. She leaped onto the cart, gasping for breath.

"Wendy...? Did you find anything?"

"Ray, listen closely. The Wendy you've been with is a fake. One day, I woke up to find nail guns and woodworking tools on my bed. When I arrived at the shack, someone was already occupying my spot. That's the Wendy you've been with today... I deliberately walked near the cameras so you could follow my path. We need to get to the bottom of this. Keep following me."

"Wait...!"

Before I could respond, Wendy bolted off.

...I had the ability to detect lies, a unique skill, and I was certain she wasn't lying.

Moments later, Wendy returned to the cart, clutching some papers.

"Hey, Ray. I've got the doppelganger's movement route and a map to track it. Luckily, the CCTV runs 24/7. The folks at the mayor's office thought I was acting strangely, trying to trace myself, but it worked in our favor."

"Wendy. You...You're not a doppelganger, right?"

Wendy stared at me as if my question baffled her.

"Um, I've been with you all day, Ray."

I contemplated the situation. Everything about her appeared genuine—her memories, emotions, and habits. She couldn't be fake. But the nagging doubt about who was real weighed heavily on my mind.

My thoughts were interrupted as Wendy expertly drove the cart.

"Where...are we going?"

"To...this house on the map. I was last seen in that area a few hours ago."

I glanced at the map and realized we were heading to my house.

"That's my house..."

"...Huh."

Wendy's doppelganger had to be close, following the trail left on the CCTV footage. I didn't have all the answers yet, but I knew that when I met Wendy, we'd uncover something new.

The cart eventually stopped in front of my house, a three-story rectangular building vastly different from the Mystery Shack. Nearby were other houses offering numerous hiding spots.

"...Hey, take this."

I handed Wendy a pair of wireless headsets and had her connect them to her phone.

"What's this for?"

"Just in case, Wendy. I'm going to investigate near my house. You stay here and keep hidden."

"But..."

"Can't you see? You could be killed the moment you recognize the doppelganger. She can replace you at any time. These headsets will help us stay in communication, even at a distance, so you won't be replaced without my knowledge."

"Fine, but then take this."

Wendy handed me her nail gun.

"It has a safety lock, so it won't shoot. Only my dad can unlock it, but he's not here... so, be careful."

"Good. Let me know if anything seems suspicious around here. I'm going to my house first."

I left the cart and approached my house, a rectangular three-story building with a different layout from the Mystery Shack. Other small buildings nearby offered countless hiding spots.

...Soon, I would face the other Wendy. What should I do when I met her? Could I bring myself to harm her if she turned out to be the real Wendy? What if she believed herself to be the genuine one?

[Drrr... Drrr...]

My phone rang, and I answered it. It was Wendy.

"You should search through all the buildings along this street, Ray. I'm sorry, but I couldn't find any more clear evidence to pinpoint my doppelganger's hiding place."

"I understand. It's okay."

"We need to hurry; that doppelganger might try to kill me, or even you, at any moment..."

Despite Wendy's urgency, I approached my house slowly. An unsolved mystery still lingered in my mind—the eavesdropper behind my computer. It was a small device that transmitted data wirelessly, and given its size, it couldn't have sent information far.

"The rooftop, or Candy's room."

Candy's room seemed less likely due to its insecurity. That left the rooftop as the most probable location.

"The rooftop it is."

I started to climb the emergency stairs beside my house, the clanging of my boots echoing through the area.

[Ray? Are you climbing the stairs?]

"Yes."

[Which stairs?!]

"..."

I didn't answer. I needed to confront her and find the truth.

[Hello?! Ray?! Can you hear me?]

"..."

[Ugh, the signal is probably dead...]

Just before I reached the last set of stairs, I dropped my earphones, ending the call. I held the nail gun and walked up the stairs slowly and quietly.

And the moment I saw the vast, open night sky...

The person I'd been seeking was standing at the rooftop's edge, her red hair gleaming in the moonlight.

I cautiously approached her, step by step. As if she sensed my presence, she turned around.

The figure that was an exact replica of Wendy faced me, her demeanor composed. I pointed the nail gun at her.

"S'up, Ray."

"Hands out of your pockets, now."

She shrugged and raised her hands in the air. I kept my aim steady.

"Looking good, Ray."

"Where's your nail gun?"

I asked her, keeping my nail gun trained on her.

"That nail gun from the carpenter's shop was stolen one Tuesday morning. Where is it?"

"It's probably in your hands, I guess."

"No. This is Wendy's dad's nail gun, which Wendy had for self-defense."

"Is it? Because I also have my dad's nail gun."

Wendy pointed to the nail gun sticking out of her pocket. It had the same design as the one I held.

"I've been carrying my dad's nail gun for some time."

"That's stolen."

"No, it's the opposite. Your gun is the stolen one. The one without any safety features, as my cousin's nail gun doesn't have any safety settings."

She started to move her hand towards the nail gun.

"Stop it! STOP MOVING YOUR HAND!"

"Shoot the gun, Ray. Then we can find out."

As she made a sudden movement, I pulled the trigger.

-POW!

The nail gun discharged, and Wendy's body tumbled over the rooftop with a faint -oof sound.

As she fell, I quickly ran to the railing, but a terrible sound rang out.

-Crack...

Had I injured her? This gun had a safety mechanism; it shouldn't be able to shoot from a long distance!

"Ray! What's going on!"

...I faced her. The girl who had climbed the stairs behind me. I pointed the gun at her from the ground and pulled the trigger.

-Pow...

The nail gun failed to fire the nail a significant distance; it fell powerlessly to the ground.

"Whoa! Man, you surprised me. I told you it had a safety lock..."

"No

."

I whispered as I gazed at the two nail guns.

"The nail gun that fell from Wendy's hand had a safety lock. The one you gave me didn't."

"..."

"And the gun without the safety lock...is the one the doppelganger used to kill me in my previous life..."

I held the gun and pointed it at the red-haired girl in front of me.

"Who the hell are you?"