The sound of metal colliding against black stone echoed through the tunnel, an arrhythmic and chaotic symphony that defined existence in Deep Mine 9. The air was thick, heavy with silica dust and sulfurous vapors rising from cracks in the floor like the breath of a sleeping beast.
For most slaves, that noise was the sound of suffering. For Nathan, it was the sound of inefficiency.
He leaned against a rotting wooden support beam, arms crossed over his thin chest, watching his two "disciples" try to work. It was painful to watch.
Ox, with his newfound brute strength and healed arm, attacked the ore wall as if it had insulted his mother, if he had ever known her. He struck with fury, sending sparks flying and dangerous stone shards whizzing through the air, but the Hot Iron ore yielded little.
Kael, on the other hand, was paralyzed. The boy "Twig" held a small chisel, trembling as he stared at the glowing rock, afraid of burning himself or missing the spot and getting scolded.
'This is pathetic. I have the strength of a crane and the eyes of a hawk, but they aren't connected. Ox is a hammer hitting the wrong place, and Kael is a compass afraid to point north. If we continue like this, we'll exhaust ourselves before noon.'
Nathan pushed off the beam and walked toward them. The heat increased with every step.
"Stop," Nathan ordered. His voice wasn't loud, but it cut through the noise of Ox's pickaxe instantly.
The giant stopped mid-swing, pickaxe suspended in the air, and looked at Nathan with the obedience of a trained dog. Kael flinched, expecting a blow.
"You are digging your own graves, not ore," Nathan said, approaching the stone wall. He felt the radiant heat on his face. "Ox, strength without direction is just waste. You are hitting the densest part of the rock. Kael, what are you looking for?"
"Cr-Cracks, Master," the boy stammered, the burn mark on his forehead glowing red and inflamed under the dirt. "But... everything looks the same. Everything shines."
Nathan sighed. He had forgotten that although Kael had the "Survivor" trait, he had no technical experience.
"Look again," Nathan pointed to a section of the wall where the reddish ore met common black rock. "Don't look at the shine. The shine lies. Look for the distortion in the air. The Hot Iron breathes."
Nathan grabbed a handful of dust from the ground and blew gently against the wall. The dust floated, but at a specific point, it was repelled upward by an invisible current of hot air coming from a micro-fissure.
"See that?" Nathan asked.
Kael's eyes widened. "The steam... it pushed the dust."
"Exactly. Where there is steam, there is an internal crack. Where there is a crack, the stone is weak. Kael, your job isn't to break the stone. Your job is to be Ox's eyes. You point, he hits. If he hits where there is no steam, it's your fault. If he hits where you pointed and it doesn't break, it's his fault."
'Shared responsibility. Creates mutual dependence. One doesn't live without the other.'
"Let's try again. Kael, point. Ox, wait for the signal."
The boy swallowed hard, approaching the boiling wall, squinting his eyes. The mark on his forehead seemed to pulse, and for a brief moment, Nathan noticed something curious: Kael didn't recoil from the heat as a normal human would. He got within centimeters of the rock.
"There," Kael pointed a trembling finger at a dark spot a meter from the ground. "There's... a little smoke there."
Ox looked at Nathan, seeking permission. Nathan nodded.
The giant swung the pickaxe, not with fury this time, but with purpose. The metal tip hit the exact spot.
CRACK!
There were no excessive sparks, no rebound. The rock made a hollow sound, and a large slab of Hot Iron ore, the size of a shield, detached from the wall and fell at their feet with a dull thud.
Ox blinked, surprised. He had barely used any strength. Kael smiled, looking at the fallen stone as if he had performed magic.
"Again," Nathan ordered, crossing his arms once more. "Get into a rhythm. Point, hit. Point, hit. Turn this into a dance, not a fight."
They started over. At first, there were mistakes. Kael hesitated. Ox hit too hard and pulverized a good stone. But after twenty minutes, something changed. A cadence formed.
Kael's whisper. Ox's strike. Stone falling. Whisper. Strike. Fall.
It was hypnotic. The pile of ore behind them began to grow at an alarming rate.
'Efficiency. The cornerstone of civilization. While other groups are fighting and competing, we created an assembly line.'
Nathan observed the "Master Points" gauge in his mind. It was still at zero, but he knew the real gain wasn't points right now; it was survival.
However, Deep Mine 9 had its own rules, and the main one was that comfort was not allowed.
Around what Nathan estimated to be two in the afternoon, the temperature changed. It wasn't gradual. It was as if someone had opened the door of a giant oven at the end of the main tunnel. The "Afternoon Wave" had arrived.
The air became liquid with heat. The torch on the wall crackled and dimmed, the oxygen being consumed by the ambient heat.
Further down the tunnel, Nathan heard the sound of bodies falling and tools being dropped. A slave screamed something about his skin burning.
Ox stopped working, leaning on his pickaxe, chest heaving violently. His face was scarlet red, and thick veins pulsed at his temples. Even with his strength, the heat was cooking his blood. Kael was already on the ground, huddled, trying to find cooler air near the earth.
Nathan felt dizzy. His vision darkened at the edges.
'Hyperthermia. We are overheating. If the body doesn't cool down, proteins denature and we die. It's now or never.
"Come here," Nathan called, his voice coming out hoarse and dry. "Sit down. Now."
He guided them to a small recess in the wall, away from the glowing ore.
"Work stops. Now we learn to survive," Nathan said, sitting in the lotus position, ignoring the pain in his legs.
"Master... hot..." Ox groaned, pulling at the collar of his rag shirt as if it were strangling him.
"Shut up and listen," Nathan said, closing his eyes to access the memory the System had implanted in his brain.
[Technique: The Turtle's Breath]
Rank: Mortal (Basic).
Effect: Reduces heart rate by 40%. Lowers body temperature through controlled exhalation. Minimizes the need for oxygen and food.
It was a simple technique, used by monks and hermits, not warriors. But here, it was the difference between life and death.
"Look at my belly," Nathan ordered, placing his hand over his own navel. "Don't breathe with your chest. The chest is for panic. Breathe with your belly."
He inhaled deeply through his nose, mentally counting to four. His belly inflated, pushing his hand. He held the air for two seconds. Then he released it through his mouth, slowly, counting to eight, making a soft hissing sound. Sssssss...
"Inhale for four. Hold. Exhale for eight. The secret is the exit. Throw the heat out with the air."
Kael, intelligent and accustomed to staying still to avoid notice, got the hang of it on the third try. He closed his eyes, placed his thin hands on his stomach, and began to mimic the rhythm.
Ox, however, was a disaster. He pulled air in with force, puffing out his broad chest like a pigeon, and released it all at once in a frustrated huff.
"Can't... no air." Ox panicked, which only made his heart race faster.
Nathan opened his eyes. Pedagogical patience wouldn't work with Ox. He needed physical stimulus.
Nathan leaned forward and, without warning, delivered a firm punch, not hard enough to injure, but enough to shock, right into Ox's diaphragm.
"Oof!" Ox expelled all the air at once, reflexively contracting his abdomen; despite not feeling pain, the reflex made him exhale.
"There!" Nathan shouted. "Feel that muscle. Where I hit. That's where the air lives. Keep that tight and pull the air behind it. Again!"
Ox focused all his limited attention on that point of impact. He inhaled, tense, and for the first time, his chest remained still and his belly moved.
"That's it. Now release slowly. As if blowing on very hot soup. Slowly..."
The trio sat there in the dust, surrounded by hell, making Sssssss sounds in unison.
A minute passed. Five minutes.
The magic wasn't visual. There were no glowing lights, no golden auras. It was just three dirty slaves breathing. But the physiological effect was undeniable.
Nathan felt his heart, which had been beating like a frantic hammer against his ribs, slow down to a steady, heavy thump-thump... thump-thump. The sensation of thermal panic receded. Sweat stopped pouring and began to simply evaporate, cooling the skin.
He opened one eye to check his disciples.
Ox seemed to have entered a trance. The giant's mouth was slightly open, his breathing rhythm slow and deep. He looked like a sleeping mountain.
But it was Kael who surprised Nathan.
The boy was motionless. And the mark on his forehead, the [Hot Iron Brand], was no longer red and inflamed. It had darkened to a shade of dry wine.
'The system said +5% Heat Resistance. It seems little on paper. But added to the Turtle technique... Kael is more comfortable here than I am. He stopped sweating completely.'
When the worst heat wave passed, about an hour later, Nathan ordered the return to work.
Now, reinvigorated (or at least no longer dying), production exploded. With the Turtle technique allowing them to work without long breaks and the refined "Eyes and Hammer" method, the pile of ore grew until it reached their knees.
At the end of the shift, Nathan looked at the result. They had, at a minimum, three times the quota required by the Foreman.
Kael looked at the pile with childish pride. "Master! We're getting meat today! The Foreman will be happy!"
Nathan gave the boy a light slap on the back of the neck.
"Idiot. If we hand all this in, do you know what will happen?"
Kael rubbed his neck, confused. "Praise?"
"No. Tomorrow, this will be the new quota. And not just for us, for everyone. If you show it's possible to do triple, they will demand triple from everyone. And the other slaves? They will kill us in our sleep for increasing their workload."
'Mediocrity is the wise man's camouflage. Never show your full strength unless it is to deal the fatal blow.'
"Ox," Nathan pointed to a dark, abandoned side tunnel that seemed to end in a dead end a few meters away. "Use that hole in the corner, the deepest part. We're going to hide two-thirds of this."
"?" Ox looked confused but grabbed the shovel. "Ox keeps stones."
"This is our reserve, Kael," Nathan explained as he helped move the rocks. "There will be days when we are sick. Days when there isn't much ore. Or days when we need to buy favors from greedy guards. Ore is money. And money is kept under the mattress."
They worked quickly to bury the surplus, covering it with loose gravel and dust to look like natural debris.
As they tidied up the mess, Ox struck his shovel against something that made a different sound. Not the metallic clink of ore, nor the dull thud of earth. It was a... dry sound. Like breaking an old branch.
"Strange, stone," Ox said, stopping.
Nathan approached, annoyed by the delay. "It's just debris, Ox, cover it up..."
He stopped.
In the flickering torchlight, embedded in the black rock wall, was something yellowish-white. It stood out violently against the obsidian darkness and the iron red.
It looked like a tube, about half a meter long, as thick as a man's arm.
Nathan reached out. Touching the surface, he didn't feel the cold texture of stone. It was porous, yet hard as a diamond.
'This isn't a stone. It's a femur. A human femur. But... the size... and the density...'
The System, which had been quiet all afternoon, suddenly awakened with an alert sound that almost made Nathan jump.
(Ding!) [Cultivation Material Detected!]
Item: Fossilized Mortal Remains (Fragment).
Origin: Bone Forging Realm Cultivator (Ancient).
Analysis: The bone marrow dried up centuries ago, but the bone structure still retains traces of Martial Essence.
Usage: Can be refined to strengthen the bone structure of mortals or used as a pill catalyst.
Nathan pulled his hand back as if shocked. He looked around, paranoid, ensuring no one in the main corridor had seen.
'A tomb. This damn mine isn't just a mine. We are digging inside a graveyard of ancient cultivators.'
He looked at the wall. If there was a bone there... what else lay hidden in the depths of Mine 9?
"Cover it," Nathan whispered, his voice trembling not with fear, but with greed. "Cover everything now. And mark this spot. No one, absolutely no one, can know we dug here."
Kael and Ox, sensing the gravity in their Master's voice, obeyed immediately, throwing dirt over the white bone.
Nathan wiped his dirty hands on his pants. A plan began to form in his mind. He needed to get strong. Normal cultivation would take months. But if he could cannibalize the strength of the dead lying in these walls...
'The Foreman wants iron. I want bones.'
"Let's go," Nathan said, picking up the basket with the "correct" amount of ore for the day's quota. "Time to get our dinner. And smile... we are just idiot slaves with luck."
They walked back to the main tunnel, three figures in the dark, guarding a secret worth more than their own lives.