The Frequency Of Rain

Tadak, tadadak—.

It was from the window, not the ceiling.

A rhythmic impact sound, yet somehow slightly off.

Even on the battlefield of 2198, a sound he had never heard even inside a cryo-sleep capsule in 2850,

it was a terribly unfamiliar yet nostalgic sound.

Lee Han-gyeol opened his eyes.

The ceiling of the lodging, as always, emitted flawless white light, but the air in the room was more humid and heavy than usual.

He sat on the bed and looked outside.

Beyond the transparent reinforced glass, gray clouds pressed low over the city’s skyscrapers, and thin streams of water snaked down the surface of the glass.

It was rain.

Not artificial mist or purification spray, real rain pouring from the clouds breaking 600 years of silence and soaking Sector 3.

“I thought it was the sound of glass breaking.”

Han-gyeol muttered as he moved to the window.

“It’s rain, Mr. Lee Han-gyeol.”

Noah’s voice flowed out from the wall speaker.

It wasn’t her usual sharp, clear tone, but a frequency that had sunk slightly, as if it were carrying a hint of moisture.

“Rain? Hasn’t it rained in 600 years?”

“Because the weather-control system was always locked to ‘pleasant clear skies.’ Today, a low-pressure system developed 0.15% off the system’s predicted path, and NOS handled it as ’natural rainfall allowed.”

Administratively, it’s just a trivial event within a 1% margin of error.

Han-gyeol placed his hand on the window.

The vibrations of raindrops transmitted through the cold glass were faint, but unmistakable.

It was the chaotic, vibrant rhythm he had heard in 2198, soaked in mud on the training center parade ground.

“Not bad for a disaster. Even more so after hearing it for the first time in 600 years.”

“It’s just 45 decibels of white noise. For androids, it’s garbage data that only increases audio filtering load by 15%. Right now 8% of the units in the square are experiencing computational delays because of this noise.”

“That’s what makes it atmospheric, you punk.”

Han-gyeol grabbed a pack of gum from his pocket and headed outside.

On the way to the office, the square looked very different from usual.

The pavement, always spotless and dust-free, had already soaked up the rain and turned a deep gray.

In the air, the scent of wet earth and the cool smell of metal mingled strangely.

Han-gyeol felt a strange sense of liberation in that unfamiliar quiet.

The Earth, freed from the system’s compulsion for ‘clear skies’, seemed to be speaking in its own voice for the first time in a very long while.

“…….”

In the middle of the square, five or six androids stood frozen.

They stood with their heads raised, taking the rain head-on without umbrellas.

“Are they all broken or something? Why are they doing that?”

Noah, who had come up beside Han-gyeol before he knew it, tapped her pad and answered.

Raindrops shattered on her shoulders too, making a small spray of mist.

Noah blinked more often than usual.

“It’s anti-sensor-scattering mode. When raindrops bead on optical lenses, it’s hard to focus. Walking efficiency has dropped by 30%, so many units have paused temporarily for safety. “

“Noah, can’t you focus either?”

“I can compensate in 0.01 seconds. My computational ability is different from ordinary units. But… this sound is really inefficient. The corridor leading to Room 402 of the Administration Building.”

In front of the large picture window stood Aria from administration and Dex from repairs side by side.

They stared blankly outside, having forgotten their work.

“Aria, what is everyone doing here? It’s past start time.”

At Han-gyeol’s question, Aria slowly turned her head.

Inside her visual sensors, instead of the usual complex administrative figures, the trajectories of water droplets sliding down the glass were being rendered in real time.

“The frequency of the rain sound… feels unfamiliar. It’s showing a 12% deviation from the ‘white noise - rain’ file NOS provided from the archive. This irregular impact sound subtly stimulates the computational rhythm of the auditory engine. Very… unfamiliar, but a strange input value that lowers system load.”

Dex from repairs also added, pressing his rough metal hand against the window.

“The vibration waveform of the glass is three-dimensional. The physical energy generated when the mass of raindrops hits metal and glass is being transmitted directly to the sensors. It’s a tactile data overload. Fascinating.”

They were defining the human feelings of ‘atmosphere’ or ‘contemplation’ in thoroughly technical terms.

But the sight of their backs, gathered blankly by the rainy window, was so much like humans 650 years ago, idling away a rainy afternoon while staring outside, it was uncanny.

Without even realizing it, they had slipped free for a moment from the shackles of programmed efficiency and become captivated by the disorderly beauty nature threw at them.

When they reached the office, Noah had a far more complex holographic map displayed than usual.

A red alarm blinked on the map near the 5th buffer zone.

“That’s enough admiring it, Lee Han-gyeol. At the outskirts of Sector 3, in the drainage pump system of the 5th buffer zone, an unexplained overload has been detected. It is presumed to be surge voltage from a lightning strike, but the sensor response is intermittent.”

“You want me to go out through this rain?”

“The weather-control system allowed the rainfall, but physical damage to infrastructure is a separate matter. Machines can’t read the ‘context’ of a rainy day. We need visual verification to see whether it’s damage hidden by brush or an actual short. The transport vehicle is waiting in the underground parking lot.”

Noah handed Han-gyeol a thick waterproof coat.

The coat smelled of dry, clean antiseptic, but the scene outside the window was a rough world completely opposite to that scent.

“Let’s go. We’ll see what’s wrong. But make sure lunch is warm today.”

The maglev vehicle waiting for them in the underground parking lot ‘Ark of Error’ had already switched to tire-grip mode for driving in the rain.

As the vehicle rose to the surface, the wipers began wiping the windshield nonstop.

Druruk, druruk.

The sound of the wipers scraping the glass mixed with the engine noise to make a strange beat.

Han-gyeol pressed his forehead to the window and looked outside.

The city was blurred at every edge, as if water color paint had been spilled across it.

When the city’s massive gate opened and they entered the buffer zone, the scenery became even rougher.

Where the paving blocks had vanished, there was a blackened dirt floor soaked with rain, and huge leaves bowed under the raindrops, unable to withstand them.

“Wow… look at that.”

Han-gyeol pointed outside.

Huge trees shook themselves to throw off the rain, and the sound, mixed with the wind, sounded like the roar of a giant beast.

Beyond the orderly city ruled by machines, it was astonishing all over again that such disorderly, powerful life force was breathing there.

“We are approaching the lightning strike site. Static levels in the air are rising, so please be careful of metal contact when disembarking.”

The vehicle came to a stop with Noah’s warning.

When the door opened, the thick smell of earth and the scent of wet brush rushed in.

It was a smell far more intense and primal than the refined air of downtown.

Han-gyeol took his first step into the rain.

The impact of the raindrops hitting his waterproof coat was heavier than he expected.

Tadak, tadak.

He stepped through the mud and headed for the drainage pump station.

Noah tracked the surrounding energy flow with a hologram panel raised beside him.

The way raindrops shattered and ran over her silver uniform made her look like a statue.

The giant metal door of the drainage pump station opened with a rusty, damp screech.

The air inside was far heavier than outside, and the mechanical heat exhaled by the huge pump engines collided with the chill of the incoming rainwater, creating a thick fog.

“Pump Unit 3 pressure threshold exceeded. It looks like foreign matter has gotten in.”

When Noah displayed the cross-section, the lower part of the pump blinked red.

Han-gyeol approached the inspection window at the bottom of the pump.

Beyond the transparent reinforced glass, in the swirling muddy water, a strange object was visible.

It was neither a broken tree trunk nor ordinary trash.

“It’s not wood. This… is it a feather?”

As Han-gyeol wiped the inspection window clean, sharp fragments with a metallic sheen were embedded between the vines.

They were tangled so tightly it looked as if they had been shoved in deliberately to stop the pump.

Intentional acts of sabotage are a pattern not found in sentient beings other than androids.

“But… this feather contains titanium alloy.”

At Noah’s analysis, Han-gyeol grabbed the manual release lever.

“Let’s pull it out first. Noah, prepare for backflow.”

As Han-gyeol put his full weight into the lever and pulled,

KWA-GANG!

A huge backflow erupted inside the pump with a deafening roar.

The tangled vines beyond the inspection window tore away, and the machine regained its smooth whirring sound.

“Normal values restored. Field verification log transmission complete.”

By the time they left the pump station, the rain had grown even heavier.

Han-gyeol stood for a moment under the pump station roof and watched the rain.

Between the foggy trees, a huge shadow flickered by for an instant and vanished.

“Did you just see that?”

“According to analysis, it’s a frequency where the cry of a large bird overlaps with the resonance of the drainage pipes. No biological threat data.”

“No, Noah. You heard it too. That wasn’t just a bird sound. There’s something like anger mixed in.”

Han-gyeol found a small object in the mud.

It was the same fragment that had been stuck in the pump earlier.

When he picked it up, the cold texture of metal stabbed into his palm.

“The feather… really is titanium. It’s cold.”

“Would you like a component analysis?”

“No. I’ll just keep it. It’s too vivid to leave as data.”

On the way back to the vehicle, Han-gyeol fiddled with the feather in his pocket.

The rain was gradually thinning, and a faint purple sky was beginning to show through the clouds.

When the vehicle ‘Ark of Error’ climbed back onto the neat asphalt of Sector 3, the raindrops had grown thin as dust and were drifting through the air.

As the wipers made a ‘druruk’ sound and wiped away the last moisture, beyond the windshield, the world of flawless order unfolded once more.

The low-saturation sunlight pouring through gaps in the clouds struck the wet outer walls of the city and scattered.

The city became vivid again, as if the watercolor paint had been washed away, but to Han-gyeol it looked somehow precarious.

“The weather-control system has completed cloud dispersal. A 0.0% chance of precipitation will be maintained for the next 72 hours.”

Noah reported indifferently while manipulating her pad.

As if annoyed by the damp air filling the car, she turned the heater up to maximum output.

Steam began rising from Han-gyeol’s wet coat.

“Hey, Noah. Aren’t you erasing it too quickly? Let it smell like rain a little longer.”

“If atmospheric humidity exceeds 65%, the joint corrosion rate of android units rises by 0.02%. Administratively, it’s better to restore dry conditions even one minute sooner.”

Han-gyeol fiddled with the metal feather in his pocket.

The cold texture of titanium pricked his fingertips.

Evolution in 2850 was blurring the boundary between organic and inorganic.

That huge shadow he had seen in the forest, and the waveform of ‘anger’ the system could not define.

It was something outside the category of a ‘perfectly normal Earth’ as calculated by NOS.

When they returned to Office 402, the corridor had already been purified back to its usual colorless, odorless air.

The androids who had been gathered by the window listening to the rain earlier were, as if nothing had happened, connected to their respective nodes and engrossed in mechanical work.

Their deviation on a rainy day seemed to have left no trace at all, as if it were just the afterimage of a brief power outage.

“Boss—.”

A low voice came from the office doorway.

When Han-gyeol turned his head, an android with her usual unfocused eyes groping at the air, Mir, was standing there.

Designed for animal translation and ecological monitoring, she always had a strangely dreamy air, unlike the other androids.

“Mir? It’s almost time to get off work. Why are you here?”

“It smells… of very thick rainwater, and of angry iron.”

Mir twitched her nose and came toward Han-gyeol.

Noah frowned beside her.

“Mir, the air quality in the current sector has been purified to 99.9%. There’s no way it could smell….”

“No. It’s coming from the boss’s pocket.”

Mir’s gaze locked onto Han-gyeol’s right pocket.

Han-gyeol flinched and took the feather out of his pocket, placing it on the desk.

Even under the cold fluorescent light, the feather flaunted its presence by emitting an eerie blue glow.

Mir cautiously reached out her hand.

The moment her fingertips touched the feather, the office fluorescent lights flickered in unison, crackling with a ‘zzzt’ sound.

Szzzt— voltage instability detected.

“Mir, let go at once!”

Noah shouted urgently, but Mir did not stop.

Her pupils deepened to purple, and her lips moved faintly.

“…The sky says it’s heavy. The ones hiding behind the clouds say the city is too noisy. So they tried to rain on it to shut its mouth.”

“What? What are you talking about?”

Han-gyeol asked, even stopping his chewing.

Mir took her hand off the feather and stared at Han-gyeol blankly.

“The owner of this feather says thank you. What was stuck in the pump was the forest’s ‘vein’. If the boss hadn’t saved it, the forest wouldn’t have been able to breathe today.”

Mir smiled brightly.

It was a programmed android smile,

but it looked far more transparent and gentle than usual.

Noah quickly deployed a hologram field around the feather.

“According to analysis, it’s not merely titanium alloy. Organic tissue and nanoscale components are bonded at the molecular level. This is… likely a ‘bio-sensor’ the forest evolved on its own to monitor or communicate with androids.”

“The forest made a machine? Does that make sense?”

“It’s been 600 years since humans left. Nature grew by feeding on the remnants left by machines, and now it’s learning the ways of machines.”

Noah stared at the analysis window for a long while, then decisively pressed the delete button.

The feather’s detailed analysis log disappeared from the screen.

“No. I’ll treat this as an ‘unidentified hardware error.’ If NOS finds out, it’ll try to burn down that forest whole for efficiency.”

Noah said that and held the feather out to Han-gyeol again.

“Please keep this, boss. Not as official data, but as your ‘unofficial souvenir’.”

Han-gyeol took the feather and put it back in his pocket.

The perfect paradise of 2850.

But beyond those walls, the forest was trying to stop the heart of the machine, and the androids were resonating with the forest’s frequency without even knowing it.

5:00 p.m.

The bell announcing the end of work rang out.

Before leaving the office, Han-gyeol left a small note in the corner of the log screen on his desk.

By the time he came out of the Administration Building, the ground had already dried almost completely.

On the park benches, androids back in daily mode were once again seated, calculating the angle of the setting sun and pretending to ‘rest.’

Han-gyeol returned to the lodging and leaned against the terrace railing, looking out at the darkening horizon.

The forest beyond the wall had soaked up the rain and turned an even deeper black, and from within that deep darkness, the cry of that huge bird he had heard earlier seemed to sound once more.

He took the metal feather from his pocket and placed it on the blank sheet of paper on the bedside table.

The feather’s sharp tip lightly scratched the paper’s surface, leaving a small mark.

The world was still fine, and the city was meticulous.

But Han-gyeol knew that tomorrow morning, when he opened his eyes again to head to work at 9, there would be one tiny new error in his chest that he would feel.

That error, in this cold city of glass, was the only gap through which he could breathe.

That was all.