Spring peaches had long fallen, the summer cicadas had gone silent, and the autumn maples had drifted away.
Time slipped quietly by amidst the monotonous yet rigorous training at Momoyama.
After nine months of relentless discipline, Ryosuke Yasui had undergone a remarkable transformation.
He had grown noticeably taller, and although still slender, he was no longer the frail boy who might break at the slightest touch.
The sickly pallor was gone—his skin now bore a healthy wheat-like tan, hardened by sunlight and sweat.
"Ha! Ryosuke! You won't surpass me today either!"
Shota's voice rang out as he dashed forward like lightning, taking the lead toward the finish line.
"Hmph… hmph… you brat, what are you so smug about…"
Ryosuke followed close behind, only a few paces away.
Rika lagged slightly further back, her little face flushed from exertion, but her steps remained steady.
After training ended, Ryosuke gritted his teeth as he stared at the number displayed on his system panel—83 days of lifespan remaining.
Even with all his training and physical strengthening, he had less than three months left to live.
At the center of the dojo, two brand-new haori were neatly folded.
One was a dark brown, Shota's favorite color.
The other was a brilliant black, with fine golden lightning patterns embroidered along the hem.
Jigoro handed the two Nichirin Blades to the young men.
Rika, being too young and physically weaker, would take the assessment a year later.
"The time for your final test has come," Jigoro said quietly. "Survive on Mount Fujikasane."
He offered no further instructions, only a silent look in Ryosuke's direction.
According to the usual training plan, even the talented Shota had needed a full year to reach the standard.
But Ryosuke was different—reckless, relentless.
While others ate, he trained.
While others slept, he trained.
Even when others were already training… he trained harder still.
With Shota by his side for the final selection, they could watch each other's backs.
Ryosuke said nothing. He simply gripped his Nichirin Blade tighter, bowed deeply to Jigoro, and descended the mountain.
He must live.
He had trained like a madman for an entire year—for this very moment.
"Shota-nii! Ryosuke-nii! Come back safe and sound!"
Behind them, Rika's voice grew fainter and fainter.
Mount Fujikasane was shrouded year-round in a sea of wisteria blossoms.
A dreamlike, pale-purple waterfall cascaded down the mountainside, forming a natural cage.
Deep within the mountains, demons captured by the Demon Slayer Corps were confined, waiting.
For the final test, participants needed to survive seven days inside this place.
Beyond the sea of wisteria, only darkness remained.
Ghostly wails echoed through the forest, and a foul stench filled the air.
Every inch of this land was soaked with the despair of the defeated.
Ryosuke was not with Shota.
Having read the "original work" before, he knew well that—aside from the infamous Hand Demon—most demons here had only eaten two or three humans, making them relatively weak.
He would use them to train—and to extend his lifespan—without Shota stealing his kills.
"Wraaagh!"
With a strange cry, a monstrous creature with sharp teeth, a long tongue, and a lizard-like body leapt from a haystack!
It lunged toward Ryosuke at incredible speed.
Ryosuke bent low, gripping his sword.
As he breathed, lightning crackled faintly around him.
"Thunder Breathing, First Form: Thunderclap and Flash!"
The sound of his blade rang out like a thunderclap!
In an instant, Ryosuke's figure vanished—then reappeared past the demon as its head was severed cleanly and turned to ash.
[Slaying a low-level demon grants +10 days lifespan. Remaining lifespan: 92 days.]
The familiar voice of the system echoed in his mind.
Ryosuke's heart pounded in excitement—this time, the move hadn't drained him much at all.
This was the power of Thunder Breathing—swift, destructive, and undeniably dazzling.
Though it was difficult to master, the results were extraordinary.
And, most importantly… it looked cool.
A single low-level demon granted ten more days of life!
Without pausing, Ryosuke darted toward another bush from which eerie howls emerged.
Aside from the Hand Demon, the lesser ones here were his for the taking.
"Strange… where are all the demons? Wasn't the Final Selection supposed to be brutal?"
A young swordsman wearing a fox mask muttered as he pushed through the jungle, scratching his head.
Akira Moriyama had been here for six whole days—six!
He had assumed his battle stance more times than he could count, yet hadn't encountered a single demon.
No way, right?
Was Master Urokodaki just trying to scare me?
Just as he thought that, a dark shadow dropped from the sky.
The stench made his pupils contract.
A hideous demon slammed into him, knocking him to the ground. His Nichirin Blade flew from his grip, landing several meters away.
You old monster! You have no martial ethics—ambushing a trainee who's trained for two and a half years?!
The demon didn't care. The scent of human flesh drove it mad, and it opened its blood-red jaws wide, ready to bite down—
Just as Akira Moriyama was about to call for help, thunder rumbled in the distance.
In an instant, a flash of lightning streaked across the sky. A boy dressed in a jet-black haori appeared beside Akira. His long sword was sheathed, and the demon's head lay severed—already reduced to ashes. The young man's ink-black hair danced in the breeze with an almost imperious elegance.
[Slaying a low-level demon grants 10 days of lifespan. Remaining lifespan: 156 days.]
Akira staggered to his feet and bowed. "Thank you… thank you. My name is Akira Moriyama."
"Yasui Ryosuke," the boy replied.
Ryosuke sheathed his sword, his lips twitching as his eyes caught the fox mask Akira wore. "Your master is Urokodaki Sakonji… Urokodaki san?"
Akira nodded.
It had been Urokodaki who had once captured the demon that haunted this mountain. That demon especially hated Urokodaki's disciples; seeing the fox mask was like salt on an old wound — it unleashed uncontrollable fury.
Based on the current timeline, Sabito and Giyu Tomioka should still be in training. This boy, then, must have been from an earlier generation. Ryosuke patted Akira on the shoulder and turned to leave.
"You'd better be careful."
"Thank you," Akira replied again.
Before Ryosuke could take two steps, a massive, malevolent aura descended upon them.
"Awooo!!!"
A roar shattered the night. The earth trembled as a monster the size of a small hill emerged from the darkness — bluish-gray skin, dozens of deformed arms writhing across its body. One enormous arm pointed directly at the fox mask Akira wore.
"Urokodaki's brat! Another one of his little fox children!" The Hand Demon's laughter cut through the air, sharp and full of bitter resentment. "I'll eat you all! I'll tear you to pieces! I'll repay Urokodaki a hundredfold for locking me up!"
Akira froze, terror gripping him. He instinctively tightened his hold on his Nichirin blade and stumbled back two steps. "No — impossible! How could a demon like you still be here?"
"Urokodaki imprisoned me here for thirty-nine years — since the Keiō era!" the Hand Demon roared, its countless arms slamming into the ground. "Unforgivable! Damn Urokodaki!"
A suffocating pressure settled over them, thick as a swamp.
Ryosuke pushed his sword free from its scabbard with his thumb; his breathing was steady and controlled. "If you don't want to die, then fight."
He moved in a blur — a streak of light that severed dozens of the demon's arms and drove straight for its neck. Akira reacted at once, his stance aligning with the rhythm of Water Breathing.
"Water Breathing — Third Form: Flowing Dance!"
Their blades flashed in unison. Enraged, one severed arm regenerated instantly and lashed out like a whip. The impact sent both fighters flying. Ryosuke clutched his chest and spat blood; Akira blacked out and collapsed.
At that moment, the fleshy mass on the Hand Demon's body compressed, and more arms shot forward. Thunder rolled again — and a figure appeared between them and the oncoming limbs.
"Thunder Breathing — Second Form: Rice Spirit!"
Lightning crackled as blades flashed; five swift slashes shattered the demon's assault.
The newcomer turned toward them. "Are you all right?"
"He won't die," Ryosuke said, forcing himself upright. Together he and the thunder user rushed the Hand Demon. Thunder raged; severed arms scattered. Though they managed to suppress the monster for a moment, both were tiring fast.
"This can't go on. We have to cut its throat," the newcomer — Shota — said coldly, his eyes tracking the next opening.
Ryosuke flexed his numb wrist; he understood the situation clearly. A demon like the Hand Demon — one that had devoured nearly thirty people — possessed an immense regenerative capacity. It wouldn't die unless its neck was severed. But its neck was shielded by a massive, hardened arm and surrounded by countless other limbs, making any approach nearly impossible.
A sweeping blow caught Shota off guard and slammed him aside. He spat blood as he crashed against a boulder; his Nichirin blade flew from his grasp, and a tear opened in his dark brown haori, blood flowing fast.
The demon laughed wildly and advanced on Shota and the fallen Akira. Countless arms, like vines of death, coiled toward them.
"Damn you!" Ryosuke coughed blood, determination flashing in his eyes. If they didn't kill this thing, no one would survive the night.
"System! Give me some points!" he muttered — a desperate, half-joking plea that hung in the charged air as the battle closed in.