Santa’s Disappearance.

08:30 AM, a Christmas morning without a hangover.

The morning in Branch District 3 was still white.

The fine chill from the nano snowflake particles Paul had sprayed, sublimating as they hit the ground, filled the entire Administration Building lobby.

Han-gyeol got off the elevator chewing on the mint-flavored gum Noah had given him the day before.

Noah and Paul, who would normally have recited all sorts of figures and said, ‘Good morning,’ today were standing face-to-face in the middle of the lobby with grave expressions.

Between them lay an unidentifiable red lump of metal, badly dented.

“Hey, what is that now? Did someone smash a fire truck or something?”

Noah turned at Han-gyeol’s question.

Her optics were tinted a deep purple, meaning ‘serious logical error.’

“Boss. A problem has occurred. The core unit of the ‘Christmas Completion Protocol’ we planned yesterday, [SANTA-01], suffered a system collapse just 30 minutes after startup.”

“Santa-01? Don’t tell me you actually made a robot Santa?”

“Technically, it’s a heavy-load delivery drone painted red, with a ‘good kid selection algorithm’ installed. But while calculating the definition of [bad kid], it couldn’t bear humanity’s moral ambiguity and destroyed itself.”

Paul, standing beside her, added in a tearful mechanical voice.

“Chief, please look at its final log. While analyzing the work attitudes of the Branch District 3 androids, between the ‘hardworking but inefficient’ unit and the ‘lazy but perfect-results’ unit, its CPU crossed the critical temperature because it couldn’t decide who should receive the gift.”

The hologram Paul projected was tangled with complex formulas.

Here, E(x) was the effort index and M(x) the morality index, but the thresholds heta_1 and heta_2 were never defined in the end.

“In the end, the guy crashed into the ventilation shaft of [Zero Sector] on the lowest floor of the Administration Building, carrying a sack full of gifts. It’s a dark area where city waste and out-of-spec androids wait.”

“Didn’t a drone just fall? Just make a new one.”

“We can’t. Inside that sack are special nutritional kits that recreate the ‘taste of the past’ you liked yesterday, Boss! It was the only way to spread the ‘Christmas error’ to the low-level units of Zero Sector!”

Noah and Paul’s gazes pinned to Han-gyeol at the same time.

It felt as if the lenses had warning text floating in them that said [replaceable organic unit detected].

“…Hey, cut that look out. I’m not doing it.”

“Boss. Machines can’t resolve moral ambiguity, but humans have the ability to decide ‘however they want.’ That’s exactly the [judgment error] we need.”

Noah, as if she’d been waiting for it, pulled out the [2850-model Santa suit] she’d hidden behind her.

It was a fiercely high-performance protective suit woven from red titanium fibers.

“Put this on, go down to Zero Sector, retrieve the sack SANTA-01 dropped, and deliver the gifts to the entities there. By the standard of ‘goodness’ you personally selected, Boss.”

“Why me? I’m a gardener, not a deliveryman.”

“Boss. The Zero Sector androids have never once in their lives seen a ‘blue sky’ laser. For them, this Christmas will be your first and last [gentle lie].”

At Noah’s words, Han-gyeol slowed the pace of his chewing a little.

The phrase ‘gentle lie’ was one he had taught Noah the day before.

The machines were learning human language, and using it again as a weapon to persuade humans.

It was a brutally clever and brutally warm way of doing things.

“…Let’s leave the beard out. It’s itchy.”

“No. The beard accounts for 42% of the visual data in the Santa silhouette. You must wear it.”

In the end, Han-gyeol grumbled and put on the red titanium suit.

In Earth’s year 2850, a real human Santa, revived after 650 years, was born.

In the deepest part of the Administration Building, the cargo elevator groaned and began descending underground.

The lobby’s gaudy neon and white artificial snow disappeared, and Han-gyeol was greeted by darkness thick with damp and the smell of oil.

The butterfly on his shoulder raised its two tails stiffly, spitting static sparks as it kept watch around him, and Noah monitored Han-gyeol’s biorhythm through the communications network.

“Boss. We’ve entered Zero Sector. The androids here are either awaiting disposal because their efficiency is low, or they’re entities using obsolete protocols. Their computing units are extremely aged, so a sudden ‘Merry Christmas’ could trigger [System Shock]. Please be careful.”

“Got it. I’ll go easy. But that red wing rolling around over there in the corner… isn’t that a Santa drone?”

In the darkness, the half-destroyed remains of SANTA-01 were visible.

Around it, old and bizarre androids he’d never seen before clustered together to gawk at the wreckage.

Han-gyeol tightened the anti-gravity backpack strap behind his back and took his first step toward the darkness.

“All right, let’s see who the good tin cans are.”

The 2850 Christmas commotion was now passing over the Administration Building’s gaudy rooftop and heading for the dark refuge of abandoned machines.

The cargo elevator stopped with a heavy metallic groan.

When the door opened, a stench no one on the surface could have imagined slammed into Han-gyeol.

The smell of rotting oil, the fishy stench of old coolant.

“…sshk. Boss, be careful. This is a blind spot where NOS’s regular purification process doesn’t reach. The floor friction coefficient is 45% lower than usual, so watch your footing.”

Even Noah’s voice over the comm had a trace of noise in it.

Han-gyeol grimaced at the smell stabbing his nose and maxed out the Santa mask’s purification function.

The butterfly on his shoulder raised its tail like an antenna and let out a low call into the darkness.

In the flashlight beam, the silhouettes of the entities gathered there were revealed.

They did not have sleek shells like Noah or Paul.

Early-2200s models.

Black grease caked over exposed wires, and their limbs were bizarrely spliced together with parts from different models.

‘…Human?’

The old guard android standing in front, with half its head module blown away, let out a busted-speaker sound.

Its lens trembled, unable to focus.

“…Scan impossible. A biotic frequency that doesn’t exist in the 2850 archive. And… a red exterior.”

Han-gyeol swung the anti-gravity backpack around to the front.

Inside the backpack were high-concentration nutritional kits SANTA-01 had been carrying, packed full of the taste of 650 years ago.

“Yeah, you guys. I’m that Santa. The tin-can old man broke down, so I came in his place.”

Han-gyeol chewed his gum and pulled out the first nutritional kit.

“Hey, you. Come here.”

At Han-gyeol’s call, the android known as 001-Alpha creaked over.

He reached out as if to touch Han-gyeol’s red suit with curiosity, then froze when he saw his greasy hands and hid them behind his back.

“What have you been doing here for 600 years?”

“…Cleaning. Sealing leaks in places no one can see, and sorting discarded parts. Even without orders from NOS… keeping this building from collapsing is my [basic mission].”

Han-gyeol wordlessly plugged one nutritional kit into the power terminal on his chest.

As high-density energy different from his usual flavorless power flowed through the circuit, his lens flashed bright blue for an instant.

“You’re good. If you worked where nobody could see you for 600 years, you deserve a prize.”

Han-gyeol gave gifts one by one to the old machines standing in line.

He didn’t need the ‘moral formula’ Noah had designed.

Han-gyeol’s standard was simple.

“In this hellish underground, are you still holding your place?”

When the backpack was about half empty, a small cleaning robot sitting in the corner nudged Han-gyeol’s ankle twice.

It seemed to be an early model of Paul, keeping a precarious balance with one wheel missing.

“…Master. I also… want to… give something back.”

The small robot opened the storage compartment in its belly.

What came out from inside was neither a data chip nor a new part.

It was a tiny glass marble, horribly old and faded.

“This is… something the Creators I last served 600 years ago… entrusted to me. They told me to keep it safe until they came back. But… no one ever came.”

Han-gyeol’s hand stopped for a moment.

Inside the glass marble, a faint rainbow shimmer swirled, as if air from 650 years ago were trapped inside.

Even after its owner left, the machine endured this dark underground for that one promise right up until the system corroded to a stop.

The machine had endured this dark underground for that one promise alone.

Noah’s voice came softly.

“…Boss. My system is currently performing a strange calculation. The action of that android is logically [resource waste]. Storing an object whose owner is absent only increases memory occupancy. And yet… why is my core measuring the value of that marble as [infinity]?”

Even Noah’s voice was mixed with an ‘error.’

The weight of time the machines had piled up over 600 years had already surpassed the arithmetic value humans calculate.

As the gift delivery neared its end, a miraculous scene unfolded on the dark ceiling of Zero Sector.

The androids who had received gifts raised their core output to the maximum and began emitting light from their own bodies.

The red, orange, and green light flowing from the old circuitry illuminated the filthy pipes and oil-stained floor, turning that place into a far more majestic and sacred [tomb of light] than the gaudy tree aboveground.

“Merry Christmas, you tin cans.”

Han-gyeol chewed his last piece of gum and filmed the scene with his camera.

In the elevator back to the surface, Han-gyeol rolled the small glass marble in his palm.

Was the warmth felt through the cold glass an illusion, or was someone’s warmth from 600 years ago really still there?

“Boss. Good work.”

When the elevator door opened, Noah and Paul were waiting.

Paul, horrified by the grime on Han-gyeol’s suit, shoved a vacuum cleaner toward him, and Noah quietly bowed her head when she saw the glass marble in his hand.

“We just received a report that the overall power efficiency of Zero Sector has risen by 12%. The machines can’t feel ‘happiness’, but it’s certain that the error Boss gave them extended their lifespan.”

Earth was still precise, and the city was cold.

But on Christmas night in 2850, Branch District 3 was connected from the surface to the underground by a single frequency.

The most inefficient, the least logical, and therefore the most beautiful frequency called [human legacy].