Who Let Her In?

The coin wouldn't stop pulsing.

It didn't burn. It didn't glow. But Min Jae could feel it in his palm—like a heartbeat that wasn't his. Slow. Patient. Alive.

He sat at his desk, the coin resting on a rune-inscribed cloth Minji had sent for magical contamination tests. So far: inconclusive.

"I don't like it," Sunwoo muttered from behind a makeshift shield of old textbooks. "Feels cursed."

"It's not cursed," Min Jae said. "It's… marked."

"Same thing. Just fancier fonts."

Goji tried to eat it again.

"No," Min Jae snapped, pulling the coin away just in time.

Goji looked betrayed.

---

Identifying the Magic

Minji appeared in the mirror, hair wild and eyes glowing with scrying spells. "I've run five trace tests," she said without preamble. "The enchantment on that coin? It's not local."

"Not Korean?" Min Jae asked.

"Not this dimension."

That stopped the room cold.

Minji nodded. "It's old-world enchantment. From the Artisan Guild, I think. You remember the whisperers' market from Rivertown?"

Min Jae did. That black tent maze where everything had a soul—and a price.

"Someone crafted this coin to function as a dimensional tracer," Minji explained. "It's like a homing beacon. Whoever dropped it could find your portal again."

Sunwoo swore. "So they tagged us?"

"Basically," Minji confirmed.

Min Jae stood. "Can you trace the trace?"

"I already did," she said. "And Min Jae…"

"…You're not gonna like it."

---

Location: Han River Underpass

The trace led to the Han River underpass, a forgotten bridge space just ten minutes from Min Jae's home. Usually full of pigeons, graffiti, and high schoolers skipping class.

Today, it was quiet.

Too quiet.

Min Jae stepped onto the stone path with Sunwoo beside him, both cloaked in minor invisibility charms. Goji wore a cardboard sign that said "NOT A GOAT."

(Which fooled exactly no one.)

They moved toward the faint mana pulse Minji had tracked. It hovered under a broken pillar—barely perceptible. But when Min Jae reached for it, the air shimmered.

And then—

"Nice of you to finally show up," a voice said.

---

The Intruder Revealed

The cloaking charm dropped.

Standing across from them was a girl.

Not older than seventeen, dressed in scavenged fantasy-world gear: mismatched leathers, utility belt, faint rune tattoos along her wrists. Her eyes gleamed with confidence. And recognition.

"Do I… know you?" Min Jae asked carefully.

She smirked. "You sold me a misfiring echo orb two weeks ago. I got memory feedback for three days. It was amazing."

Min Jae blinked. "Wait—you're the girl with the singing dagger?!"

"I upgraded," she said, pulling a dagger that now purred. "And you owe me for making me addicted to peanut dust."

Sunwoo blinked. "She's a fan?"

She bowed slightly. "Name's Rina. You probably never asked. That's fine. Most sellers don't."

---

How Did She Cross Over?

"How the hell did you get through?" Min Jae demanded. "The portal is keyed to my mana. No one should be able to enter—especially not from your side."

Rina shrugged. "I didn't enter your portal."

"You didn't?"

"I reverse-synced your beacon charm," she said proudly. "You left one in a mana crate I bought. It still pulsed after I returned home."

Min Jae slapped his forehead. "Minji's tracking tech…"

"Exactly. It wasn't locked. So I amplified it, timed my location with its pulse window, and rode the return energy like a wave. Portal surfing."

Sunwoo muttered, "That's… actually genius. Insane. But genius."

"I know," she said, beaming.

---

Why Is She Here?

"Why are you here?" Min Jae asked warily.

"Curiosity. And opportunity." Rina pulled out a folded scroll. "This world? No mana saturation. No ambient interference. That makes it perfect for storing and stabilizing spells."

"So… smuggling," Min Jae deadpanned.

"Entrepreneurship," Rina corrected.

"Illegal entrepreneurship," Min Jae growled.

Rina raised her hands. "Look, I don't want your world. I just want… access. Temporarily. Maybe once a week."

"Absolutely not."

Rina smiled. "Then let's negotiate."

Min Jae raised an eyebrow.

And then she dropped a bombshell:

"I know who's watching you."

---

A Hidden Agenda

"Third Market? Index?" Sunwoo asked.

Rina shook her head. "Older than both. I found relics on your trade goods. Enchantment markers no one's used in centuries. You think you're building your own brand?"

Min Jae tensed.

"They're building you," she said.

"You're saying someone is crafting my rise?"

"I'm saying you're walking into a role someone else prepared. And they're almost ready to cash in."

Min Jae stared at her. "Why tell me this?"

"Because," Rina said, "if someone's going to play dimensional chess with your life... I want in on the board."

---

Trust? Not Yet.

Min Jae crossed his arms. "So you want access to my world, my portal, and my trust... in exchange for one conspiracy theory?"

"I want five minutes of trust," she replied. "Enough to show you the rune they left on your basement wall."

His blood ran cold.

"What wall?"

Rina turned. "The one behind your mirror. You've never checked, have you?"

She stepped back.

"See you soon, Gatekeeper."

Then activated a personal recall glyph—and vanished.

---

Back Home

Min Jae didn't hesitate.

He ran down to the basement, pulled the mirror off the wall, and aimed a mana light.

There—so faint even Goji didn't react—was a sigil.

A sealed rune, hidden behind suppression glyphs.

Old magic.

Not his.

Not Minji's.

Something ancient.