Awakening, and the First Door

The air in the Emergency Medical Center at Korea University Hospital Main Branch, on the dawn of a first-year resident’s ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠first shift, was torn apart by the sharp stench of disinfectant and the piercing wail of alarms. Exactly three minutes had passed since the cardiac arrest support request dropped into the residents’ group chat. The monitor above the bed in Sector 3 was already drawing wildly erratic waveforms. Ventricular fibrillation—VF.

In front of the bed that had become a battlefield, the chief resident on night duty was shouting urgently.

Nurses pushed heavy equipment through the crowded space, their paths crossing in a frantic dance. Baek Ijun slipped through the chaos without hesitation and stepped beside the intern who was sweating profusely as he compressed the patient’s chest.

“I’ll take over.”

The intern, his face deathly pale, stepped back with a ragged breath. Ijun placed both hands over the lower part of the patient’s sternum. The compressions began.

One. Two. Three.

The heavy resistance of the rib cage transmitted through his fingertips and straight into his brain. This was his first time applying his full body weight to chest compressions in a real clinical setting. He pressed down deeply, using the recoil from his waist to maintain a steady rhythm.

‘To catch a system error, you need consistent output with zero variables.’

It was the kind of rigorous calculation drilled into him since his days as a biomedical engineer. But after one minute, then two, a vast gap began to open between the calculations in his head and the harsh reality of his body.

Last night—technically the night before his first day as a resident—Ijun had not slept a wink. It wasn’t from excitement. As a first-year, he had spent the entire night running simulations in his head: how to optimize the movement paths for dozens of patients on the ward, how to build routines that would minimize procedural errors.

That brutal sleep deprivation chose this exact moment—when life and death hung in the balance—to reach its peak.

Three minutes. Severe dizziness began gnawing at the edges of his vision, turning everything black. The sensation in both arms pressing on the patient’s chest grew heavy, like waterlogged cotton. The sharp noises around him dulled, as if he were submerged in deep water.

‘This is central nervous system shutdown caused by sleep deprivation. I’ve reached my limit.’

His vision bleached white at terrifying speed. There was no fear. In the final semester of his biomedical engineering degree, he had chosen to return to medical school—not to fix perfectly controllable machines, but to treat people, full of irregular variables. And now, on the first dawn of this long-delayed residency, he was about to collapse pathetically on the emergency room floor.

A remarkably calm, almost dry calculation flashed through his mind. Yet one single thought caught in his chest like a fatal error in an otherwise perfectly controlled system.

‘I’ve never performed a single operation.’

He had entered the operating room countless times as an intern. He had silently handed ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠instruments to his seniors and held the suction for ten straight hours to keep the field clear. But never once had he held the scalpel with his own hand, made the incision with his own judgment, and cut into living flesh.

It wasn’t simple regret. It was something closer to a deep, vicious remorse far worse than he had planned for.

The monitor’s alarm stretched out in one long, unbroken tone. Ijun’s vision went completely dark. The chief’s urgent shout receded into an unfathomable abyss.

When he opened his eyes, the place was no longer the emergency room filled with the smell of disinfectant and blood. It was an endlessly vast, eerily silent space. Towering wooden bookshelves reached all the way to a ceiling that could not be seen, stretching out in endless rows. Between them stood massive iron doors, firmly locked, arranged at regular intervals.

‘Probability that this is a hallucination created by sleep deprivation affecting the visual cortex.’

Ijun rose to his feet with calm composure. Out of habit, he placed two fingers on his radial artery. His pulse maintained a perfectly normal rhythm. His breathing was steady. The terrible overload that had crushed his chest just before he collapsed on the emergency room floor was gone without a trace.

Then, from within the deep shadows of the enormous bookshelves, an overwhelming presence whose form was difficult to discern revealed itself. An immense pressure that made even breathing feel laborious weighed heavily upon the entire space.

It was a heavy voice that made even the tiniest speck of dust in the space tremble. Ijun gazed at the empty shadow and spoke softly.

“Excuse me? Don’t you think that’s a bit too unfriendly? Telling me to open them without any explanation at all.”

There was no answer.

“Even if this is a tutorial, you should at least provide some guidelines so I can proceed to the next step.”

The silence continued.

“Then please activate the exit button first. There’s a patient waiting for me outside.”

It felt like dealing with an outdated, feedback-free legacy AI. And at that exact moment, a translucent holographic interface rose into the air with a cheerful notification sound. There were five tabs.

Ijun slowly reached toward the first tab, [Encyclopedia]. The moment his fingertip touched the hologram, the first and second iron doors that had been firmly shut swung open at the same time with a heavy metallic groan.

The moment the messages appeared, a massive tidal wave of data slammed mercilessly into Ijun’s mind. It was not a simple injection of knowledge. The complex anatomical structures of the human body, the maximum tension tissues could withstand before tearing, the perfect hydrodynamic dissection trajectories the scalpel must follow to avoid tangled vessels—all of it forced its way in.

The flat, two-dimensional knowledge from the surgical textbooks he had memorized as text was being forcibly rearranged inside his brain into an entirely new form of three-dimensional engineering visual data. It was an overwhelming computational overload that far exceeded the brain’s basic processing capacity.

“It’s problematic to force an install like this without obtaining user consent first.”

Before he could even finish speaking in his relaxed tone, the space began to shake violently. His vision went cold and heavy once again, and everything faded to black.

“Hey! Baek Ijun! Snap out of it!”

With the rough shout, his eyes flew open. The emergency room’s harsh white fluorescent lights poured down like a waterfall. The chief resident was looking down at him with a sweaty, fierce expression.

Ijun braced himself against the floor and slowly pushed his upper body up. He opened his mouth to answer, but no voice came out. His vision was exploding. The emergency room landscape no longer looked normal. Hundreds—thousands—of translucent layers floated and swirled chaotically in the air. The muscle contractions of the surrounding nurses, the speed of blood flow beneath the patient’s skin, the minute tension distributions of the organs—all of it was converted into merciless visual data that hammered his optic nerves without mercy.

‘What the hell is this? There’s too much data. I can’t filter it.’

A wave of dizziness crashed over him. The sheer volume of information far outpaced his brain’s processing speed, making it feel like his mind was screaming. This was not a blessing or a power. It felt closer to an uncontrollable, horrific curse.

“Can you even hear me? Are you okay?”

The chief shook Ijun’s shoulder roughly. Within the torrent of visual noise, Ijun barely managed to focus on the patient on the bed. Over the patient’s chest wall, a blueprint of blue bones and a map of red blood vessels swirled together in a dizzying dance.

“Doctor, the tension distribution around the patient’s sternum is asymmetrical. The flow resistance from the left ventricle has also decreased, and the tension in the intercostal fascia is snapping sharply at the lower right quadrant.”

The unfiltered data poured straight out of his mouth in its raw form. Even Ijun himself didn’t fully register what he had just said. The chief’s mouth fell open in disbelief.

Only after seeing the chief’s dumbfounded expression did Ijun realize his error.

‘I recited the engineering analysis data verbatim. In a clinical setting, that kind of report is a one-way ticket to being treated like a lunatic. Shut up and find only the most dangerous signal.’

Ijun squeezed his eyes shut, then opened them again. He consciously pushed away the blue and red information floating in the air. The chaotic layers blurred and faded until only one vivid red signal remained, pulsing darkly at the lower right edge of the patient’s sternum, just beneath a rib. Above it, visual data clearly displayed a hairline fracture in the bone.

‘It’s a rib microfracture. That’s all I’ll say.’

Ijun steadied his breathing and slowly rose to his feet. He perfectly restored his voice to its usual soft, calm tone.

“I’m sorry. It seems I hallucinated for a moment due to sleep deprivation. Chief, I suspect a microfracture in the patient’s lower right rib area.”

The chief’s brow furrowed sharply.

“I was the one compressing the chest until just now. I felt the resistance of the rib cage deviate slightly at the lower right side. It would be safer to check the chest wall line with portable ultrasound.”

Ijun’s voice was so firm and confident that it was hard to dismiss as an excuse. The chief studied Ijun’s eyes for a moment, then clicked his tongue and ordered the intern beside him to bring ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠the ultrasound machine.

Fortunately, after defibrillation, the patient’s rhythm had returned to normal sinus rhythm. The ultrasound probe, coated with gel, glided over the patient’s chest wall. The chief’s gaze locked onto the monitor. Soon, a short, thick exclamation burst from his lips. It was exactly the point that matched the trajectory of the red layer only Ijun could see.

The chief put away the ultrasound device and looked at Ijun again. The bewilderment had vanished, replaced by a strange sense of understanding.

“Your tactile sense is insanely sharp. Even though your stamina is completely shot.”

“I’m glad we caught it before it led to major damage.”

“Go sit in the corner of the station. And don’t collapse in front of a patient again.”

Ijun answered with a gentle smile and stepped back from the bed. As he walked toward a quiet corner of the emergency room, a familiar white coat approached and blocked his path. It was Lim Dohyeon, his classmate and fellow first-year Neurosurgery resident who had gone through intern year with him.

“Whoa~~ What the hell happened… How do you manage to dramatically collapse on the emergency room floor on your very first day, man?”

Dohyeon spoke in his usual cheeky tone.

“I didn’t collapse. It was the result of pushing my stamina to its absolute limit. Is Neurosurgery so relaxed that you can come sightseeing in someone else’s ER from the crack of dawn?”

Ijun shot back leisurely. Dohyeon let out a snort of laughter.

“The rumor that you collapsed already reached the Neurosurgery on-call room, so I came to see for myself. But you look perfectly fine.”

“I forced myself to get up because I knew you were coming. I’ll collect the viewing fee later in the form of an iced Americano.”

Dohyeon shoved his hands into his coat pockets.

“From the chief’s face, it looked like you nailed something important right before you hit the floor… What was it?”

“Just got lucky and felt it with my fingertips.”

“Luck is a skill too~~. Looks like you didn’t get marked on your first day, so I’ll be going! Hang in there!”

Dohyeon gave a light wave and left the emergency room. Ijun stared at the empty space where he had been, then checked his own vision again. The violent flood of data that had filled his sight was gone. However, every time he blinked, a faint afterimage of the standby interface lingered in the corner of his vision like a ghost.

‘There’s no physical way to turn it off. This data is being rendered directly onto my visual cortex.’

He waved his hand through the air, but the system did not respond. Overwhelming data could help a doctor grow, but it could also become poison that paralyzed judgment if left unchecked. Just like that terrible moment earlier when he had rambled incoherently.

But mechanical data could never make judgments on its own. If he wanted to prove and use the overwhelming intuition the system provided in real clinical practice, controlling it would ultimately have to be entirely his responsibility.

‘I will not be dragged along by the layers. I will completely master this system.’

Ijun slipped both hands into the pockets of his white coat. The cold metallic head of his stethoscope touched his fingertips. A cheerful hospital broadcast announcing the start of the morning slipped through the noise of the emergency room.

Thirty-one years old. The path he had returned to in order to heal people instead of machines. A perfect weapon capable of suppressing uncontrollable errors had been placed in his hands.

The real first day of Baek Ijun, first-year resident, had officially begun.