The next morning, Ha-rin burst into Jae-hyun's office, hair damp from the rain that hadn't been forecasted anywhere.
"You're not going to believe this," she said.
He barely looked up from his holographic display. "At this point, I believe anything that doesn't involve quarterly reports."
"I found a place," she said breathlessly. "It wasn't on the map yesterday."
That got his attention. "Where?"
"Underground district, below Insadong. People call it the Memory Market."
He frowned. "Never heard of it."
"Exactly. It's new because time made it old."
He blinked. "You've started speaking in paradoxes."
"Just come," she said, grabbing his hand.
The Memory Market wasn't listed in any directory.It lived under an abandoned subway line, accessible only through a graffiti-covered stairwell behind a bookstore.
When they descended, the air grew warmer, denser—thick with the scent of incense and electricity.
Stalls lined the narrow tunnels: vendors selling old photographs, broken watches, cassette tapes whispering half-remembered songs.Everywhere they looked, people traded not money, but memories.
A woman handed over a silver coin and received a snow globe.When she shook it, she smiled and whispered, "My wedding day."
Ha-rin's skin prickled.
Jae-hyun murmured, "We're inside a black market for time."
They wandered deeper.A vendor called out, "Buy a day you've lost! Half-price if it still hurts!"
Another shouted, "First love, genuine edition! No refunds!"
Ha-rin couldn't help it—she laughed. "You can't make this up."
Jae-hyun smiled faintly. "You underestimate human nostalgia."
They stopped at a stall with no signboard.An old man sat behind a counter stacked with journals and sketches.He looked up as they approached. "Ah. The constants."
Ha-rin froze. "You know us?"
He nodded. "You've been here before. Each time, a little closer."
She leaned in. "Closer to what?"
He opened one of the journals.Inside were drawings identical to hers—same lines, same strokes, even the same ink smudges.
She whispered, "These are my sketches."
He smiled. "They belong to time, not to you."
Jae-hyun's voice was quiet but firm. "What happens when the twelfth echo ends?"
The man's eyes gleamed. "Time stops asking. It starts choosing."
He slid a small pocket watch across the counter—its hands frozen at 12:12."For when memory forgets again," he said. "One of you will need it more than the other."
Ha-rin reached for it, but Jae-hyun's hand closed over hers first.They looked at each other, the world narrowing to that single touch.
The old man smiled softly. "Ah. The constants never change."
Outside, the rain had stopped.They walked through the quiet alleys of the underground city until the light above grew brighter.
"Do you believe him?" she asked.
"I don't know," Jae-hyun admitted. "But I believe us."
She looked at the watch in her palm. "Then we hold the twelfth heartbeat ourselves."
He nodded, eyes soft. "Until the world remembers."
As they climbed the stairs back to the surface, neither noticed the faint shimmer of the old man's stall fading into air—as if it had never existed.
On the last step, the pocket watch in Ha-rin's hand clicked once.
Tick.
The sound was small, but the world shifted.Billboards blinked. Clouds reversed. A child's laughter echoed backward for a moment.
And then everything went still again.