The morning after the rooftop rain was the kind that pretended nothing extraordinary had happened.But inside Luma Group, time felt slightly off.Meetings ran a few minutes late without reason. Emails arrived before they were sent. The elevators skipped floors.
And in every corner of the building, if you listened closely, you could hear it — the faint, almost tender sound of a heartbeat hidden beneath the hum of machines.
Yoon Ha-rin walked through the corridor holding her sketchbook like an artifact, her heart still syncing to that twelve-beat rhythm.
Every step felt measured, precise — as if someone else was keeping count.
Kang Jae-hyun was already in his office, screens glowing around him with half-deciphered data.He looked up when she entered."You came early," he said.
"I didn't sleep," she replied.
He smiled faintly. "Good. Then we're synchronized."
She dropped the sketchbook on his desk. "I think I found it."
He frowned. "Found what?"
"The location." She flipped open the sketchbook to a page she didn't remember drawing — a map of the Korean peninsula, overlaid with faint clock faces and wave patterns radiating out from the south.
"The third echo isn't in Seoul," she said quietly. "It's beneath it."
He leaned closer. "How deep?"
"Below the old Hanam Reservoir — that's where the waves point."
Jae-hyun tapped a few keys, pulling up archived data. "That area was sealed after a landslide ten years ago. It's restricted."
Ha-rin met his gaze. "Then it's perfect."
He grinned despite the weight of it. "You really have a thing for breaking into forbidden places."
She smiled. "Only when time insists."
By evening, they were driving along the highway toward Hanam.The rain had followed them again — soft, persistent, like a shadow that refused to be left behind.
The road was empty. The city lights faded into dark hills, and mist curled over the asphalt like slow smoke.
Ha-rin watched through the window. "It's strange," she said. "Everywhere we go, it feels like we've already been there once before."
Jae-hyun glanced at her. "Maybe we have. Maybe this road's been waiting for us to remember."
She smiled. "You're learning to sound poetic."
He smirked. "It's your fault. Contagious."
By the time they reached the reservoir, the rain had turned into drizzle.The area was fenced off, overgrown with ivy and moss.But the air felt charged — thick, humming, alive.
They slipped through a gap in the fence and walked toward the concrete spillway.
The heartbeat was louder here.Twelve steady thumps pulsing through the ground.
Ha-rin stopped. "It's under us."
Jae-hyun knelt, brushing away mud and debris until his hand found metal — a hatch half-buried in earth, marked with the faint imprint of the Echo Division's logo.
"Bingo," he whispered.
Together, they pried it open. A rush of cold air spilled out, smelling of dust, metal, and time long forgotten.
Ha-rin peered into the darkness below. "You first."
He raised an eyebrow. "Always the gentleman's curse."
They descended the narrow ladder into a dimly lit tunnel lined with old pipes. Their footsteps echoed softly — each sound coming back half a second late, as if even their echoes were delayed by time itself.
At the end of the tunnel, a door waited — steel, rusted, but still powered. A faint red light blinked above it.
Ha-rin pressed her hand against the panel.It beeped once.
The display lit up with two names: Yoon H. / Kang J.
Her breath caught. "It knows us."
"Of course it does," he murmured. "We built it."
The door slid open with a low hiss, revealing a vast underground chamber.Rows of servers lined the walls, glowing faintly in alternating blue and gold light.And in the center of the room, suspended above a circular pool of water, hovered a translucent sphere of light — beating like a heart.
"The Third Echo," Jae-hyun whispered.
Ha-rin stepped forward, her reflection shimmering in the pool below. "It's beautiful."
"Beautiful things are usually dangerous," he said.
"Then maybe so are we," she whispered.
As they approached, the heartbeat grew stronger — not loud, but felt, resonating in their bones.The sphere pulsed once, and for a moment, their reflections shifted — showing versions of themselves in other clothes, other ages, other lives.
A voice filled the chamber.
"Sequence recognized. Constants detected."
Jae-hyun grabbed her hand instinctively.
"Twelve calibrations remain. Choose: Continue or Terminate."
Ha-rin looked at him. "If we stop it…"
He finished, "…the loop ends. But we might, too."
"And if we continue?"
"Then it rewrites everything. Again."
She hesitated, then whispered, "If the price of time is memory, then I'd rather lose everything than forget you."
He looked at her for a long moment, eyes glinting in the dim light.
"Then we continue," he said.
Together, they reached out.Their fingers touched the sphere — warm, weightless, alive.
The light flared, swallowing the room in white.
And for one suspended moment, everything stopped — not frozen, but aligned.
They heard their own voices overlapping across timelines — laughing, whispering, promising.
Then the light dimmed, leaving only silence and a single glowing word across the wall:
CONVERGENCE: 1 OF 12 COMPLETE.
Ha-rin exhaled shakily. "We started something."
Jae-hyun nodded. "Or something started us."
Outside, the rain had stopped.The world felt still again — too still.
Neither of them noticed the faint shimmer of silver on Ha-rin's wrist where the sphere had touched her.
A mark.A circle.Ticking softly beneath her skin.