Chapter 1 The Black Invitation

Ding!

The soft jingle of the café doorbell chimed as Kawin stepped inside. He brushed the mist of rain off his shoulders and ordered a hot latte, then made his way to a corner table near the window. Outside, the rain continued to fall relentlessly as people hurried by with no clear destination in sight.

Nothing about today seemed unusual—

Until he opened his briefcase.

Amid the piles of research documents, a salary slip, and a pending termination notice he had yet to sign, something appeared that didn’t belong there at all.

A black card.

It was the size of a credit card, smooth and glossy like glass. There was no sender's name, no logo—only one sentence printed in silver reflective lettering at the center:

"You are invited to the grand opening of a new aquarium—one you should not decline."

He flipped it over, but there was nothing else. No names, no addresses. Just a message:

"Tomorrow, 6:00 PM. A car will be waiting for you—wherever you are."

Kawin stared at it for several minutes until a staff member approached and said, "Someone left this for you."

The waitress handed him a cream-colored envelope with a smile that seemed... uncertain. Inside was a hand-drawn map—no street names, no landmarks. Just lines. Attached was a note, typed with a typewriter:

"Every experiment begins with someone who never intended to participate – D.M."

Despite his instinct telling him to discard it all, he now found himself sitting in a taxi the following night, en route to the destination on the map.

No reason.

No motive.

Only a strange, inexplicable voice in his head whispering,

"You should go."

The road was wet, deserted, devoid of homes or civilization. Overgrown grass lined both sides, and flickering streetlights flashed like warning signals. The taxi came to a stop in front of a tall iron gate that opened just as they arrived.

No signs.

No guards.

No staff.

Only a small plaque with fading letters:

"LUCID OCEAN - PRIVATE ZONE."

He stepped inside with growing unease, not out of fear of ghosts—but of people. He had always found humans far more terrifying than spirits.

As he walked, lights flickered on in sync with his footsteps. It was as if the building already knew he would come.

The sealed lobby of the aquarium loomed before him. It was vast and silent. Thick glass walls enclosed various tanks, all unlit. In the center, a round table and twelve identical chairs stood arranged with unnerving precision.

Two people were already there.

A woman in a red suit sat cross-legged, sipping coffee from her own mug. She looked him over slowly, as if evaluating something.

The other, a rugged man in a leather jacket, nodded briefly before returning to his laptop.

"You're the eleventh," the woman said.

"What does that mean?" Kawin asked.

"The eleventh out of twelve... who received the invitation," she replied flatly. "But not everyone accepts it."

Her words unsettled him. Ever since receiving that black card, nothing made sense. And yet, every time he tried to dismiss it, something in his subconscious insisted:

"You have to go."

Soon, more people arrived—a teenage girl with dyed purple hair, a middle-aged man who looked like a driver, an elderly woman with a cane, and a young man in a delivery uniform.

They had all received the same black card. Yet none of them knew who had sent it.

When the last person entered, the lobby door closed with a click. Locked. A speaker in the ceiling crackled to life:

"Welcome to the Forbidden Aquarium. You have all been chosen to witness the final experiment. From this moment on... any breach of the rules will be taken as full acceptance of the consequences. The 13 rules will now be announced. There will be no second warning. Remember them... for you will not hear them again."

The room fell silent. Every ear tuned in.

"The rules are as follows. Listen carefully... again:

Do not touch the glass.

Do not feed the fish.

Do not say the name of any creature aloud.

Do not retrace your steps.

Do not look into an empty tank.

Do not take photos or record video.

Do not ask about the past.

Do not remain alone.

Do not open closed doors.

Do not mention the outside world.

Do not touch the water.

Do not read the writing on the glass.

Do not challenge the rules."

The announcement ended. Lights turned on one by one across the surrounding tanks—some empty, some filled with debris, and others too dark to see inside.

"What the hell is this..." the purple-haired girl whispered.

The driver walked to the door and tried to pull it open. It wouldn’t budge. "We’re locked in," he confirmed.

Just then, the speaker returned with one final message:

"Within a few hours, the system will begin testing each of you according to the rules. If you break them, there will be consequences—irreversible ones. If you survive, you’ll understand what survival truly means. If you fail... you will become the next subject of observation."

The woman in the red suit set down her coffee. She seemed composed, prepared.

"Alright, everyone," she said. "I’m Arisa. And no, I don’t think this is just a prank by some reality show."

"Why not?" Kawin asked.

"Because I’ve seen this name before... in a file from the Department of Science. The facility was shut down ten years ago. An entire research team disappeared."

Before anyone could ask further, a loud sound echoed. A side door in the lobby creaked open, and a dim blue-lit hallway revealed itself, light turning on slowly as if inviting—or forcing—them forward.

At the end of the corridor stood a large glass door. Behind it was the Central Tank Room.

The beginning of everything.

And in that moment, a voice—one that wasn’t his own—whispered inside Kawin’s head:

"Keep walking... follow your curiosity."