Ryosuke Yasui's movements were so smooth and seamless that they caught Jigoro completely off guard.
"Oh? What's your name?"
"Ryosuke. Yasui Ryosuke."
Jigoro's expression turned serious. "Slay demons? With that frail body of yours?"
His voice carried undisguised skepticism and cruelty.
"If a mere breeze can blow you over, and you cough up blood after a few steps, how could you even lift a sword? The training of the Breathing Techniques crushes and rebuilds the body inch by inch! Your weak frame will collapse before you even see a demon!"
The Demon Slayer Corps faced countless dangers; they could be wiped out at any time. Because of that, trainers had to constantly raise new recruits to replenish the ranks and maintain the Corps' fighting strength. Time was precious.
No one would waste it on a dying man with less than a year to live.
Ryosuke knew Jigoro's words were true—harsh, but real. This body was indeed a burden.
He suddenly lifted his head. His eyes were bloodshot from pain, yet a wild fire burned within them—an almost insane obsession.
"Master! My family was slaughtered by demons… but I can do it!" Ryosuke roared. "If I can't wield a blade, I'll bite it! If I can't swing a sword, I'll hurl myself at them! As long as I can kill demons—no matter the suffering—I'll endure it!"
"If my bones break, I'll set them and train again! If I cough up blood, I'll swallow it and fight again! Please, Master! Give me a chance!"
The room fell silent, save for Ryosuke's ragged breathing.
This was his last path—a desperate struggle to live.
The sharpness in Jigoro's gaze slowly softened. He looked at the thin, frail boy before him, who seemed as if he might crumble at any moment. That madness in his eyes—reckless, desperate—reminded Jigoro of something long buried in memory.
He exhaled and said solemnly, "Come with me."
He had relented.
Ryosuke's eyes widened with surprise and gratitude as he followed.
As they walked down the corridor, the sunlight was dazzling. They soon reached a broad training ground behind the mansion, surrounded by peach trees heavy with blossoms.
This was the Training Ground. The ground was compact and level, with wooden stakes, stone weights, and weapon racks lined neatly along the edges.
A boy and a girl were training there. The boy looked about thirteen or fourteen, lean and agile, with tousled brown hair and movements as nimble as a monkey's. The girl was slightly younger, her hair tied in a simple bun, her small frame moving with quiet focus.
"Shota! Rika!" Jigoro's voice rang out.
The two halted mid-swing and looked over.
Shota grinned, eyes gleaming with curiosity as he studied Ryosuke. "Who's that?"
"Ryosuke Yasui," Ryosuke said hoarsely.
"Shota Kiritani," the boy replied easily, then gestured to the girl beside him. "This is my sister, Kiritani Rika."
"Hello…" Rika bowed slightly, shyly. Her voice was soft and gentle.
Ryosuke nodded back—a brief but sincere greeting.
From his memories, he knew these two didn't appear in the original story. That likely meant they wouldn't survive the Final Selection at Mount Fujikasane.
After all, the Hand Demon—an early-stage monster—was lurking there. If not for Tanjiro… well, let's just say his headbutt-and-water-slice combo had been a miracle. The title of "Water Pillar" was truly well-earned.
"Ryosuke's health is poor," Jigoro said bluntly. "But he's chosen the path of a Demon Slayer. From today, he'll train alongside you."
He gave them a hard look. "Shota! Rika! Basic physical training—fifty laps around the track! Ryosuke…"
His eyes flicked over the boy's trembling body and pale face.
"Twenty laps. You can walk if you must, but you'll finish. Now—begin!"
Shota and Rika responded in unison and sprinted off, their footsteps light and quick.
Ryosuke Yasui took a deep breath and followed behind.
The training field was about 500 meters in circumference.
Twenty laps... ten kilometers...
He had never run that far before — not even in his past life, let alone in this one.
Before he had even completed half a lap, a sharp pain shot through his lungs, and his steps grew unsteady.
But in order to survive, Ryosuke gritted his teeth and forced himself to keep moving. Cold sweat poured down his body.
Shota and Rika passed him again and again.
As Rika ran by, she glanced at him with concern.
Three laps... four laps...
Ryosuke Yasui felt like he would explode if he took another step!
Sweat blurred his vision, and all he could hear was the pounding of his heart.
He had only one thought in his mind:
Finish the run! You must finish the run! This is the first step!
When Shota and Rika finished their day's training and went back inside for dinner, Ryosuke was still running.
In the end, he nearly crawled across the finish line.
Ryosuke trembled all over, half-kneeling on the ground, his face pale as a corpse. His ragged coughs seemed to tear his body apart.
Inside the house, Rika couldn't help but glance at Jigoro.
"Jigoro-sensei, is Ryosuke really going to be okay?"
Jigoro looked toward the boy and replied calmly,
"He'll be fine. You two eat first."
"But—"
Just as Shota was about to speak, he saw Ryosuke on the training field suddenly stand up.
His eyes were fixed on the wooden sword resting on the weapon rack.
Dragging his heavy legs, he staggered forward step by step.
"Hey! He…" Shota froze.
Is this guy out of his mind?!
Jigoro didn't say a word. He only nodded slightly, the corners of his mouth curving up for a brief moment.
Ryosuke gripped the wooden sword. Its weight nearly snapped his wrist.
He planted his feet and, recalling what he had seen Shota and the others practice earlier, raised the sword above his head.
"Haah—!"
The blade swung down, cutting through the air with clumsy, weak force. His stance was crooked and unsteady.
But Ryosuke didn't stop.
The wooden sword rose again—then fell once more.
This was his will battling desperately against his frail body.
Shota and Rika stood frozen, forgetting to eat or even speak, watching in stunned silence as the boy continued swinging the sword.
When night fell, the world was quiet.
The pain from training kept Ryosuke awake.
Then, the door opened.
Jigoro stepped inside, carrying a bowl of medicine and a small jar of medicinal oil.
There were no lamps lit — only the cool moonlight streaming through the narrow window.
Just as Ryosuke was about to speak, Jigoro set the bowl down, covered his hands with the oil, and began to massage Ryosuke's trembling leg muscles.
His touch was firm, with a practiced rhythm that pressed into the stiff flesh, bringing both pain and release.
"Ah—!"
Ryosuke clenched his jaw, breathing hard.
After a while, the pain gave way to a strange burning warmth — and then, comfort.
When Jigoro finally stopped, Ryosuke collapsed onto the mat, drenched in sweat and utterly exhausted.
Jigoro lifted the bowl to his lips.
The medicine was so bitter that Ryosuke could barely swallow it.
"Master... Master..." Ryosuke's hoarse voice broke the silence.
In his previous life, his parents had died early, leaving him to live as a corporate slave, struggling to survive in the cracks of society.
Jigoro's sudden kindness struck deep into his heart.
"Can I... can I call you Grandpa, like the others do?"
Jigoro coughed lightly, his tone deliberately gruff.
"Call me whatever you want! Just stop whining!"
He grabbed the empty bowl, stood, and turned to leave.
But the moment his back was to Ryosuke, his expression softened. For an instant, he looked almost gentle — the kind of gentleness that could fill a room with the warmth of spring.
As Ryosuke watched the old man's retreating figure, a warmth bloomed within him.
He buried himself beneath the covers, his shoulders trembling quietly.