Black Nail

[0.] World Merger

The television flickered in the quiet apartment, casting a cold glow across the room.

A breaking news broadcast cut through the silence.

Grainy footage showed something moving in the city's sewer system-humanoid shapes made of shifting darkness. They didn't walk like people. They *slid* through the tunnels like they belonged there more than light ever did.

The reporter's voice was tense.

"Authorities are investigating unidentified entities appearing beneath multiple districts. Citizens are advised to avoid underground infrastructure..."

A diagram flashed briefly-sealed tunnels, red zones, military blockades.

Then the broadcast shifted abruptly.

A different headline took over, almost like the world refused to stay serious for more than a few seconds.

A missing figure: **Julien Blair**, a popular otaku content creator. No uploads. No sightings. Just silence.

Then again-another cut.

A rising global idol: Gemi Madison. Concert footage. Applause. A smiling face that didn't quite match the strange timeline of her sudden fame.

The boy on the couch stared at the screen without reacting much, like he had already learned not to trust how the world changes tone so quickly.

He stood up.

The fridge hummed when he opened it. Light spilled across his face. Normal. Predictable. Safe, even if barely.

Instant noodles. A boiling pot. Steam rising.

The kind of routine that pretends nothing is wrong.

He sat down and finally spoke, mostly to himself.

"Hydro Undergrove... fifteen. Living alone. Not because I want to, just because it ended up like this."

A pause.

"I'm not really popular at anything. Photographer, maybe. Not that it matters much."

The noodles softened in the bowl.

Outside, the city was quiet-but not peaceful.

There was a faint vibration in the air. Almost like distant machinery grinding against reality itself.

Hydro stopped eating.

For a moment, the room felt... misaligned. Like the space itself had shifted slightly off its axis.

The TV flickered again behind him.

No signal.

Just static.

Then-something underneath the static.

A sound that didn't belong in a living room.

A low, dragging resonance.

"RRRRR..."

Hydro didn't turn immediately.

He just listened.

Then finally:

"...So it's starting again."

The air behind him darkened.

Not like a shadow from light-but like something replacing the idea of space itself. A thin distortion formed in the corner of the room, bending the edges of reality inward like a wound trying to open.

Hydro stood up slowly.

No panic. No rush.

Just recognition.

The distortion widened slightly.

A pressure filled the room-like the feeling before a storm breaks, except the storm wasn't weather. It was *something else trying to arrive where it didn't belong*.

Hydro exhaled.

"...Doesn't matter."

But his eyes sharpened.

The darkness stabilized into a faint vortex, barely contained, humming with something ancient and incorrect.

Then-

A memory that wasn't fully a memory slipped into place.

Not words.

Not images.

Just weight.

A world that had already ended once.

A war that didn't belong to human history.

And something beneath it all... still waiting.

Hydro's expression didn't change much, but something in him clicked into alignment.

Far away-too far to measure normally-something vast stirred between layers of existence. A structure like a black castle buried between dimensions, surrounded by a silent army that did not sleep.

Millions. No-more.

Something like an army that treated time as optional.

Then-

The vision snapped.

Hydro was back in his apartment.

The noodles had gone slightly cold.

The TV was off.

But the feeling didn't leave.

A voice, quiet but absolute, seemed to sit behind his thoughts.

Not spoken aloud.

Recognized.

Hydro stepped toward the window.

Outside, the city still pretended it was normal. Sirens hadn't started yet. People hadn't realized they should be afraid.

Not yet.

He adjusted his glasses.

"...If they're already leaking through the sewers, then the surface won't hold for long."

A pause.

Then, softer:

"I guess I don't get to stay home tonight. The Apartment's only for rent."

He picked up his jacket.

The apartment suddenly felt smaller than it had a minute ago.

Behind him, the air flickered once more-like something testing the boundary between worlds.

Hydro didn't look back this time.

He walked out.

And somewhere far beneath the city, something answered his movement.

Not with sound.

With attention.