The sun blazed mercilessly overhead as Kairo stood at the base of the towering mountain. The iron weights clamped around his ankles dragged like anchors, threatening to root his small feet to the earth.
"Go!" the King roared from behind.
Kairo gritted his teeth, jaw locked tight. He forced one foot forward. Then the other. Each step sent fire racing up his calves. His legs screamed in protest, lungs burning as though filled with molten glass, sweat pouring down his face in stinging rivers.
I can't stop. I won't stop.
By the halfway mark his knees buckled without warning. He crashed onto the jagged rocks, palms scraping raw. Blood trickled warm across his skin, mixing with dirt and dust.
Tears welled up, hot and blurry. His tiny body begged to collapse, to curl up and surrender.
But then his father's words echoed in his mind—Never quiver. Never bow to fear.
Kairo slammed both bloodied fists into the ground.
"No... I can't stop here! Not yet!"
Shaking, gasping, he pushed himself up. One agonizing step at a time, he dragged his body higher. His chest heaved violently. Vision blurred at the edges. Yet when he finally staggered onto the peak, he lifted his face to the endless sky and let out a shaky, breathless laugh.
"I... I did it..."
No time to rest. The trial had only just begun.
Stumbling, knees threatening to give out, Kairo forced himself back down the slope—then up again. And again. The iron weights dug deeper with every stride, carving raw lines into his skin. Blood soaked his sandals. His lungs felt like they were on fire.
By the fourth ascent he could barely see. The world tilted and spun. Every muscle shrieked for him to stop, to collapse, to never rise again.
But deep inside his chest, something pulsed faintly—the same burning warmth he had felt the night the contract was sealed.
No... I'm not just any child. I have to become strong... stronger than anyone... for Father... for the kingdom...
With one final, desperate cry, Kairo drove his legs forward. He staggered down the last stretch of the path until his feet finally touched the training ground.
"F-Father... I... I did it..."
His legs folded. He collapsed face-first into the dirt.
The King's heavy boots crunched across the ground. For a long moment he simply stood there, looking down at the trembling boy who had poured out everything he had. Then, slowly, a proud smile spread across the King's scarred face.
"Well done, my son," he said, voice rumbling with deep approval. "You didn't just climb a mountain... you climbed your weakness. Remember this day, Kairo. This is the day you began walking the path of a King."
Even through the haze of exhaustion, Kairo's cracked lips curved into a faint, exhausted smile.
And then everything went black.
The next morning, Kairo lay motionless on the wide bed, every muscle in his body throbbing with deep, bone-aching pain from the brutal mountain trial. His legs felt like lead, his arms heavy as iron, and even breathing pulled at raw, overworked tendons. Yet beneath the exhaustion, a quiet, stubborn pride flickered in his chest.
"...I survived," he whispered, lips curving into a tired, crooked smile.
He let his eyelids drift closed again, willing sleep to take him—
Ding!
Kairo's eyes snapped open.
A translucent square of pale blue light hovered in the air directly in front of his face. Glowing golden letters shimmered across its surface, crisp and impossible.
[Welcome, Player.] Your growth has been acknowledged.
Kairo blinked rapidly, rubbing his eyes with the heels of his palms. The window didn't vanish.
"...W-what the—?! A... a pop-up window?! Just like the other isekai... I finally have one!"
His voice cracked with disbelief and rising excitement. The window flickered again, new text scrolling into view.
You have entered the Tutorial Stage. Training and hardships will unlock hidden potential. Your path as [Future King] begins now.
Kairo's jaw fell open. He sat up slowly, wincing as fresh pain lanced through his back.
"P-Player? Future King?! What is this... some kind of... game?"
As though answering his unspoken question, another line appeared below.
Status Window Unlocked. Would you like to open it? [Yes / No]
Kairo swallowed hard. His hand lifted, trembling slightly. He hesitated—then realized he didn't need to physically touch anything. The moment the thought formed, the window responded.
Yes.
A new screen unfolded before him, clean and glowing.
[Name]: Kairo [Age]: 7 [Title]: The Chosen Son, Future King [Strength]: ?? [Agility]: ?? [Endurance]: ?? [Magic Power]: ??? [Skills]: None
Kairo's eyes widened until they hurt.
"S-Strength... Agility... Endurance... This is like an RPG! But why are there question marks? Hmm... I guess I have to level up to see my actual stats."
Before he could process further, another notification flashed into existence.
New Quest Assigned: Become Worthy of the Sword. Reward: Skill [Beginner Swordsmanship].
Kairo bolted fully upright, ignoring the sharp protest of his abused muscles. His heart hammered against his ribs.
"Quests?! Rewards?! This... this is insane!"
The windows hovered for a few more seconds—silent, expectant—then dissolved into motes of light that faded into the morning air, leaving only the quiet of his room.
Kairo stared at the empty space where the screens had been. His breathing came fast and shallow. Questions crashed through his mind in a dizzying rush.
Was this because of the contract? The shadowy figure? Or... is this what the prophecy actually meant?
Whatever the answer, one truth settled over him like cold certainty.
His path was no longer just grueling training under the King's watchful eye.
He was now... a Player in this world.
And the game had only just begun.
Kairo stared at the glowing blue screen hovering before him, pulse hammering in his ears.
"This... this is amazing! If I have quests and stats, then maybe—"
The words died on his lips. The screen flickered violently. Letters twisted and warped, scrambling into jagged static.
"Eh? W-What's happening?!" Kairo gasped, leaning forward.
The text fractured completely:
[ERROR. ERROR. SYSTEM MALFUNCTION.]
With a soundless crack, the status window shattered like fragile glass, shards of light dissolving into nothing.
Kairo's eyes widened in panic. He thrust his hand forward instinctively.
"N-no...! Come back! System, open! Status window—!"
Nothing. The air remained empty. Silence pressed down, thick and suffocating.
Despair clawed up his throat. His shoulders slumped, breath hitching—
Ding.
A new window materialized—smaller, darker, edged in cold crimson light. Its presence felt heavier, almost oppressive.
[Listen, Kairo.] Do you think strength is given? Do you think shortcuts exist? Foolish child. Your previous system will never return. You will suffer. You will bleed. Only then will you become strong.
Kairo froze. His mouth went dry.
"W-what...? Why...?"
The window continued without pause, words sharp and merciless.
I will not grant you strength. You must EARN it. Now then... study.
Before Kairo could react, a thick tome materialized in midair and dropped heavily onto his lap with a solid thud. The cover gleamed under the morning light—deep crimson leather embossed with elegant gold lettering:
How to Be a Good Leader
Kairo blinked, jaw slack.
"A... a book?!"
The window flickered once more, the text almost mocking.
Your first trial is knowledge. No warrior, no king can rise without wisdom. Begin studying. Fail to learn... and you will never grow.
A final line appeared, small and final:
You may summon books. That is all this system will grant. No powers. Only knowledge.
The window vanished.
Kairo's hands tightened around the book's edges until his knuckles whitened. His heart pounded so hard he could feel it in his temples.
"...So... no shortcuts... huh?"
He traced the gold lettering with a trembling fingertip. The tome felt impossibly heavy—not from its weight, but from what it represented. No instant skills. No cheat abilities. Just words. Effort. Time.
Yet somehow, that made the path ahead feel even more real.
Kairo drew in a slow, steadying breath. His eyes lifted, determination hardening in their depths.
"...Alright," he whispered.
He opened the cover to the first page.
The faint morning light spilled across the words as the boy began to read.
No grand system. No easy power.
Only the long, hard road of a true leader.
And Kairo would walk it—step by painful step—until he became the king this world needed.
Kairo sat cross-legged on the wide bed, the heavy tome open across his lap. His lips moved silently as he traced each line with a fingertip.
"'A true leader must never turn away from the cries of his people...'"
The words settled deep inside him, pressing against his young chest like an invisible hand. He exhaled slowly, feeling their gravity sink in.
Suddenly—BANG!
The grand double doors of his chamber flew open with a resounding crash.
The King filled the doorway, clad in midnight-black armor chased with crimson accents. His cloak snapped behind him like spilled blood, the fabric rippling with every purposeful stride. His sheer presence seemed to thicken the air itself.
"Kairo," he said, voice deep and unyielding. "We must hurry."
Kairo's head snapped up, eyes wide. The book nearly slipped from his fingers.
"F-Father?"
The King crossed the room in three long steps, his gaze sharp and unwavering.
"There is war ahead. Our scouts have confirmed it. You will not fight—not today—but you must come. You must see."
Kairo's grip tightened on the tome until the leather creaked. His voice came out small.
"See... war?"
The King knelt, bringing his scarred face level with Kairo's. One massive hand settled gently but firmly on the boy's narrow shoulder.
"A future king must witness both peace... and bloodshed. Words alone will not teach you. You must feel the weight of the battlefield."
Kairo's throat closed. His pulse thundered in his ears.
"But... I-I'm only seven—"
For a single heartbeat, the King's stern features softened—eyes crinkling at the corners with something almost tender.
"Yes. And that is why you will not fight. But you will watch. You will learn. The battlefield is cruel, Kairo. But it is also truth. A king who hides from it cannot protect his people."
Kairo stared into those steady eyes. His breath hitched. Slowly, he gave a single nod.
"...I understand, Father."
The King rose to his full, towering height. He extended one gauntleted hand.
"Good. Then come with me. Today... you will take your first step into the reality of rulership."
Kairo hesitated only a moment. Then he placed his small hand into the King's enormous palm. The grip was warm, solid, unbreakable.
He clutched the mysterious book to his chest with his free arm, its weight a quiet anchor against the storm he was about to face.
Together they left the chamber—down marble corridors, past bowing guards, out through the palace gates.
Toward the distant thunder of war drums.
Toward the clash of steel rising like a storm.
Toward the smoke that already stained the horizon black.
Kairo's heart pounded against his ribs, fear and resolve twisting together in his chest. He did not let go of the King's hand.
Not once.
War drums rolled in the distance like approaching thunder, steady and ominous. Inside the command tent, lamplight flickered across the broad war table where maps lay pinned open. Colored markers showed enemy positions, supply lines, and the jagged line of the border river. Generals stood in a loose circle, armor glinting, voices low as they debated formations.
Kairo stood quietly at his father's side, barely tall enough to see the table's surface. His small fingers twitched against the edge of his tunic, eyes darting over the lines and symbols he had only begun to understand.
"Father..." His voice came out soft but steady.
The King turned, his stern gaze softening just a fraction at the sight of the boy.
"Yes, Kairo?"
Kairo bit his lower lip, then pointed at the red arrows sweeping toward their lines.
"I've been thinking... what if we use defense, not offense? If we rush forward, we'll lose too many. But if we stay firm... if we force them to come to us, their haste will destroy them."
A ripple of amusement passed through the generals. One older man with a scarred cheek let out a low chuckle.
"Hah... the boy speaks like a tactician already."
But Kairo wasn't finished. His eyes gleamed with sudden, strange clarity, words tumbling faster.
"And about magic... the enemy will definitely use fire magic, right? Then why don't we make it backfire? We line the front with burning torches soaked in oil. They'll think it's just a signal—or maybe water barriers. When they cast fire, their own flames will ignite the oil instead. They'll burn themselves alive."
The generals' smiles vanished. They leaned forward, eyes narrowing, exchanging quick glances.
Kairo lowered his gaze, frowning as though listening to something only he could hear.
"Even in the future they'll think twice before using fire again. And we need traps—make them believe we're losing, then have a wizard disguised as a soldier use earth magic to collapse the ground under their advance. The archers handle the rest. We also have to prepare for sudden attacks from the rear—surprise flanks. They'll try to encircle us."
He hesitated, voice dropping to a near-whisper that sent a chill through the tent.
"...But... for some reason, I feel like I could erase their memories. Alter them. Make them believe we won by normal means. Keep the tactic secret forever. But I wish I had the power to make them fear us. We can do it without magic, though. It's confidence. Make our soldiers think they're going to die—go into battle as if death is certain. But before you die, make your death worth something. Don't be consumed by cowardice."
The tent fell utterly silent. Even the distant drums seemed to fade into nothing.
The King stared down at his son, eyes wide. For the first time since Kairo had known him, the giant ruler's expression wasn't calm, nor fierce—it was shaken. A muscle ticked in his jaw.
"Kairo... where did you learn such things?"
The boy looked down, fingers twisting in the fabric of his tunic. His voice came out small.
"...I don't know. It just... came to me. Do you... believe me?"
The King slowly placed one massive hand on Kairo's head. The touch was firm but careful. Then a low, rumbling laugh escaped him—deep, proud, almost disbelieving. It grew until it filled the tent.
"Hahaha! My son... my clever, terrifying son. At seven years old, you already think like a master of war."
The generals bowed their heads in unison, murmuring in quiet awe. Respect replaced amusement in every line of their faces.
The King's eyes gleamed as he looked down at Kairo.
"Very well. We shall use your tactics." His voice lowered, carrying a weight that silenced the room again. "But remember this, Kairo: genius can win battles, but only kindness wins kingdoms. Never forget that. Well... I have a feeling I didn't need to teach you that, but remember it."
Kairo nodded slowly. His heart pounded so hard he could feel it in his throat. Somewhere deep inside—beneath the fear, beneath the strange clarity—a faint, cold smile seemed to brush against his mind. The shadowy figure from his nightmares watched, pleased.
And so, a child's strategy would decide the fate of the battlefield.
The King straightened, turning to his generals with renewed fire in his eyes.
"Prepare the torches. Disguise the earth mage. Ready the archers for the collapse. We meet them at dawn."
Kairo stood motionless, still clutching the edge of the map. The war drums rolled louder now—closer.
He swallowed hard.
The weight of what he had just set in motion settled over him like a cloak made of iron.
But he did not look away.
The battlefield stretched wide beneath a sky the color of bruised iron. Smoke already drifted in thin veils across the plain, carrying the sharp stink of oil, sweat, and fear. Banners snapped in the wind—royal gold and crimson on one side, the enemy's jagged black and scarlet on the other. Soldiers stood in rigid lines, shields locked, spears bristling like a forest of steel. The low rumble of war drums pulsed through the ground itself.
Kairo sat astride a calm gray mare beside the King, small hands clenched around the reins until his knuckles whitened. His body trembled faintly—not from cold, but from the sheer weight of what he was about to witness. His heart hammered so hard he could feel it in his teeth.
"Steady, Kairo," the King murmured without looking down. His voice was low, steady, a rock in the rising storm. "Watch carefully. This is the truth of battle."
Across the field, the enemy line surged forward—a black tide of steel and fury. Kairo's breath snagged in his throat as he saw their mages step to the fore, staves raised high. Crimson light gathered in their palms, growing brighter, hotter.
"They're casting fire magic!" a general shouted from somewhere behind.
Kairo's fists tightened on the reins. Now... it's time.
The King lifted one gauntleted hand.
"Water magic—release it!"
A chorus of royal mages answered in unison. Their voices rose in a low, resonant chant. Shimmering streams of liquid arced into the air—thick, glistening, catching the sunlight like molten silver. To the enemy it looked like water barriers, a desperate defense.
Laughter rolled across the field—cruel, confident.
"Water barriers? Pathetic! they have fall into our traps" an enemy commander bellowed.
Fireballs launched in a blazing arc—hundreds of them, streaking red across the sky like falling stars. They struck the "water" in a deafening roar.
WHOOSH!
The battlefield erupted.
The false water ignited into a roaring sea of flame. Orange and black swallowed the enemy's front ranks in an instant. Screams tore through the smoke—high, panicked, inhuman—as soldiers burned alive, consumed by the very magic they had unleashed. Armor melted. Banners caught and flared like torches.
Kairo's eyes widened. His mouth went dry.
My plan... it worked.
The King's voice thundered over the chaos.
"Forward! Crush them while they burn!"
The royal army surged like a breaking wave. Steel flashed. Horses screamed. The disoriented enemy line buckled, then shattered.
Victory came fast—too fast.
But as the smoke began to thin, something shifted inside Kairo. His vision blurred at the edges. A sharp pain lanced through his temples. His chest tightened until he could barely breathe.
No... they can't know... this tactic must remain a secret...
The words weren't spoken aloud, but they rang in his skull like a command. His eyes glowed faintly—soft silver light that no one else seemed to notice. A silent pulse rippled outward from him, invisible, unstoppable.
The surviving enemy soldiers staggered, faces twisting in confusion. One dropped to his knees, clutching his head.
"W-What...? How... how did we lose?" another muttered, voice cracking. "They... they just outmaneuvered us... right?"
Even on Kairo's side, generals blinked, frowning.
"Strange... wasn't their fire magic stronger? No... perhaps I misremembered..."
Kairo clutched his head with both hands, a sharp gasp escaping him. Pain throbbed behind his eyes, hot and bright. He didn't understand how—or why—but his will had rewritten their memories. The truth of the oil trap vanished from their minds like smoke.
The King turned slowly. His sharp gaze locked onto Kairo. For a heartbeat, shock flickered across the giant's face—then pride, fierce and unshakable.
He leaned down from his warhorse, voice dropping to a whisper meant only for the boy.
"My son... today you are not just a boy. Today, you are the blade that guarded this kingdom you have caused confusion that will make them less focus on the battle and they will be in panic mode because of your new magic."
Kairo's small hands trembled on the reins. Tears stung his eyes—not from fear, but from the crushing weight of what he had done. He had shaped the battle. He had burned men alive with their own power. He had reached into their minds and changed what they believed.
And he was only seven.
He nodded once, eyes blazing with a mixture of terror and resolve.
The war drums had fallen silent.
The battlefield belonged to them.
But the cost settled on Kairo's narrow shoulders like iron chains he could already feel tightening.
The battlefield still smoldered in patches, thin columns of black smoke curling into the sky. The King reined in his massive warhorse at the edge of the command rise, turning to Kairo with a calm, almost gentle expression that belied the blood still drying on his armor.
"Okay, my son. Time to go." His deep voice carried easily over the settling wind. "I am the king, remember. You need to fight with our soldiers one day. I came here today because I wanted to teach you. Well then... see you."
Before Kairo could respond, the King wheeled his mount. The horse exploded forward in a surge of raw power, hooves thundering across the trampled earth. In seconds the giant figure was gone—swallowed by the front lines where the last pockets of enemy resistance still fought.
Kairo's breath caught. From his vantage point he watched the King charge straight into the thick of the remaining foes. Thousands of enemy soldiers rushed to surround him, forming a tightening ring of spears and blades. The King was alone now, cut off from his main force.
Yet he did not falter.
Steel flashed in wide, brutal arcs. Each swing of the King's greatsword carved through armor and bone like paper. Bodies fell in heaps around him. He moved like a force of nature—unhurried, unstoppable. A spear glanced off his pauldron; he caught the shaft, yanked the man forward, and ended him with a single downward stroke. Another soldier lunged from the side; the King pivoted, armor screeching, and drove his elbow into the man's helm, crumpling it inward.
The enemy generals shouted orders, trying to close the circle tighter. But the King pressed deeper, carving a path of ruin. Blood sprayed across his crimson cloak. His horse reared, trampling men beneath iron-shod hooves.
Then the royal army arrived.
Like a tide breaking over rock, they crashed into the enemy rear. Swords rose and fell. Arrows darkened the air. The disguised earth mage slammed his staff into the ground—earth split, swallowing dozens of men in a sudden chasm. Archers on the rise loosed volley after volley, thinning the encirclement.
The enemy line shattered.
The King emerged from the center of the carnage, raising his sword high. A final, thunderous cheer rose from his soldiers as the last enemy banners toppled.
Victory.
Banners of gold and crimson flew high above the field once more. The King marched at the head of his returning army, armor dented and stained dark with blood, yet he rode as though untouched by fatigue. Entire enemy territories had crumbled beneath his blade today; their kings lay broken, their armies scattered.
Kairo sat quietly on his horse behind him, small hands tight on the reins. The weight of everything he had seen pressed down on his chest until it hurt to breathe.
So this is war... Father... you're like a storm. Nothing can stand before you. My tactics... they barely mattered. One part worked, but the rest... they didn't even need it. I'm pretty useless. Thank goodness I'm in a strong kingdom. They win with raw strength alone.
As the army made its triumphant march home, Kairo's gaze drifted.
The horses beneath them were enormous—far larger and more muscular than any from his old world. Yet they moved with tireless grace, hooves striking the earth in perfect rhythm. Not a single beast panted or faltered, even after hours of battle.
He drew a slow breath. The air felt thick, rich, almost electric in his lungs.
Yes... the oxygen levels... they must be higher. I remember the book Father gave me: during Earth's dinosaur era, oxygen was dense. Creatures grew massive. They had endless stamina. Even after all that fighting, not one soldier is gasping. What kind of monstrous endurance do they have?
His eyes wandered again. A giant beetle crawled up a roadside tree, its iridescent shell the size of his head, mandibles clicking softly.
Even the insects... so big. So this world really follows the same rules.
His heart gave a strange, heavy thud as realization settled deeper.
No wonder I don't tire so easily. No wonder I can carry those weights, endure the training. This world itself... is nurturing me. Making me stronger.
Kairo lowered his gaze to his own small hands gripping the reins. They no longer shook.
I'm not the same Kairo anymore. I'm not that boy sitting in front of a screen, wasting days. Ever since that contract... my memory is sharper. My thoughts clearer. I see connections I never could before.
He lifted his face to the bright sky. Stars were already faintly visible in the daylight, faint silver pinpricks against blue.
One day... I will die. And maybe then I'll return to my old world. But until then... this world is mine. Even without TV, without games, without any of my old comforts...
A faint, quiet smile touched his lips.
...this world feels so alive. So real. So good.
He closed his eyes for a moment, letting the steady rhythm of marching boots and hooves wash over him.
Somewhere deep inside, he knew his journey had only just begun.