Yasui Ryosuke's whole performance flowed so smoothly that it caught Jigoro completely off guard.
"Oh?" Jigoro raised an eyebrow. "What's your name?"
"Ryosuke. Yasui Ryosuke."
Jigoro's expression hardened. "Slay demons? With this body of yours?"
There was no attempt to soften his words—only blunt doubt and cruel honesty.
"A gust of wind could knock you over. Run a few steps and you cough up blood. Can you even lift a sword? Swing it? Breathing training is about grinding your bones to dust and reforging them inch by inch through pain."
"This broken shell of yours would collapse before you ever laid eyes on a demon."
Life in the Demon Slayer Corps was a gamble with death. You never knew which mission would be your last.
That was why cultivators had to train new recruits constantly, feeding fresh blood into the Corps to keep its combat strength from breaking. Time was precious.
No one would waste it on a dying invalid with less than a year to live.
Ryosuke knew Jigoro was telling the truth—bloody, merciless truth.
This body was a burden.
He suddenly lifted his head. His eyes were bloodshot from illness, yet the fire burning in them was shockingly fierce—borderline insane, driven by obsession.
"Senior! My entire family was killed by demons—I can do this!!"
Ryosuke roared, "If I can't hold a blade, I'll bite with my teeth! If I can't swing a sword, I'll crash into them with my body!"
"As long as I can kill demons! As long as I can gain the power to slay them! I'll endure any suffering!"
"If my bones shatter, I'll piece them back together and keep training! If I cough up all my blood, I'll swallow it back down and keep fighting! Senior—please! Give me a chance!!"
The room fell deathly silent, broken only by Ryosuke's ragged breathing.
This was his only path to survival. A resolve forged from desperation—living, no matter the cost.
The scrutiny on Jigoro's face slowly faded.
He stared silently at the boy before him—so thin and fragile it looked as though he might stop breathing at any moment.
That fire in his eyes… that reckless, all-or-nothing obsession…
It reminded Jigoro of something long buried. Something distant.
He exhaled.
"Come with me," he said solemnly.
In the end, his heart softened.
Ryosuke's eyes lit up as he hurried after him.
They passed through a long corridor, the sunlight outside almost blinding.
Behind the residence lay a wide open clearing. Peach trees surrounded the area, branches heavy with blossoms in full bloom.
This was the Peach Mountain training ground.
The earth had been packed firm and level. Wooden posts, stone locks, and weapon racks lined the edges.
At the center, a pair of siblings were training.
The boy looked about thirteen or fourteen—lean and agile, with messy brown short hair. His movements were quick and lively, like a monkey.
The girl was a bit younger, her hair tied into a simple bun, her figure petite and delicate.
"Shota! Rika!"
Jigoro's voice rang out.
Both stopped mid-swing and turned in unison.
Shota grinned broadly, his eyes bright as he looked at Ryosuke. "Who's this?"
"Yasui Ryosuke," Ryosuke said, his voice hoarse.
"Kiritani Shota!" the boy replied cheerfully, then pointed at the girl beside him. "And this is my little sister—Kiritani Rika!"
"H-hello…"
Rika bowed shyly, her voice soft and gentle.
Ryosuke nodded in return.
From what he remembered of the original story, neither of them existed.
Which meant there was a high chance they would die during the Final Selection on Mount Fujikasane.
After all, the Hand Demon lurked there.
If not for the protagonist—Tanjiro—pulling out that absurd headbutt-plus-water-breathing decapitation combo at the last moment, that fight wouldn't have ended well.
"Head Hashira" wasn't just a joke—it was earned.
"Ryosuke's body is weak," Jigoro said bluntly. "But he's resolved to walk the path of demon slaying. From today on, he'll train with you."
He swept his gaze over the three of them, his voice suddenly turning sharp.
"Shota! Rika! Basic endurance training—fifty laps around the field!"
Then he looked at Ryosuke's swaying figure and deathly pale face.
"As for you… twenty laps! Walking is allowed, but you must finish. Now—move!"
Shota and Rika were already used to this.
They answered crisply and sprinted off, light-footed and fast.
Ryosuke took a deep breath and followed behind.
One lap around this field had to be at least five hundred meters.
Twenty laps… ten kilometers…
Forget this life—he hadn't even run that far in his previous one.
Before he even finished half a lap, his lungs began to burn, his steps turning unsteady.
But for the sake of living, Ryosuke clenched his teeth and forced himself forward. Cold sweat poured from his body—not from heat, but weakness.
Shota and Rika passed him again and again.
When Rika ran by, she glanced at him with worry in her eyes.
Three laps… four laps…
Ryosuke felt like taking one more step would make him explode.
Sweat blurred his vision. His ears rang with the thunderous pounding of his heart.
Only one thought remained in his mind.
Finish it. I have to finish. This is the first step.
By the time Shota and Rika completed their day's training and went inside for dinner, Ryosuke was still running.
In the end, he practically crawled across the finish.
His whole body trembled as he dropped to one knee, his face pale as a corpse. His broken coughing sounded like it was tearing him apart from the inside.
Inside the house, Rika couldn't help looking toward Jigoro.
"Grandpa… is Big Brother Ryosuke really going to be okay?"
Jigoro watched the boy in silence.
"He'll live. You two go eat."
"But—"
Shota was about to say something when he saw Ryosuke—somehow—stand up again.
Ryosuke's gaze locked onto the wooden swords on the weapon rack. Dragging his lead-heavy legs, he staggered toward them step by step.
"Hey—he's—!"
Shota's jaw dropped.
Is he trying to kill himself?!
Jigoro said nothing. He only gave a faint nod, the corner of his mouth lifting ever so slightly.
Ryosuke gripped the wooden sword. Its dull weight nearly crushed his wrist.
He planted his feet apart.
Using hazy memories, he mimicked the movements he'd seen Shota and Rika practice, raising the sword overhead.
"Haaah—!"
The blade came down, slicing uselessly through the air. The strike was clumsy and weak, the posture laughably crooked.
But Ryosuke didn't stop.
Down. Up. Down again.
This was his will fighting a desperate, losing battle against his frail flesh.
Shota and Rika stood frozen, forgetting their dinner, forgetting how to speak—watching in stunned silence as the boy continued to swing.
Late at night, when all was quiet.
The pain from training kept Ryosuke awake.
Then the door opened.
Jigoro entered, carrying a bowl of medicinal decoction and a jar of medicated oil.
The room was unlit, moonlight spilling faintly through a narrow window.
Ryosuke was about to speak when Jigoro set the bowl down, dipped both hands into the oil, and pressed them onto Ryosuke's spasming, trembling leg muscles.
The pressure was heavy, the technique rhythmic and strange. Stiff muscles loosened instantly—only for the piercing pain to be ground even deeper into him.
"Nggh—!"
Ryosuke's teeth rattled as he gasped.
After a moment, a peculiar warmth seeped through the soreness, bringing unexpected relief.
He didn't know how long passed before those hands finally stopped.
Ryosuke collapsed limply onto the futon, drenched in sweat.
Jigoro lifted the bowl to his lips.
The medicine was bitter beyond belief, but Ryosuke swallowed it down with effort.
"Mas… Master…"
His voice was hoarse. He hesitated.
In his previous life, his parents had died early. As a burnt-out shut-in wage slave, he'd scraped by alone in society's cracks.
Jigoro's sudden care stirred something deep inside him.
"C-can I… call you Grandpa too? Like they do?"
Jigoro coughed a few times, his tone deliberately impatient.
"Call me whatever you want! Stop being so damn noisy!"
He snatched the empty bowl and turned to leave.
But the instant his back faced Ryosuke, the atmosphere completely changed.
The old man's expression softened, practically glowing with invisible peach-blossom bubbles.
Watching his retreating figure, warmth welled up in Ryosuke's chest.
He buried himself under the blanket, his shoulders trembling silently.