"Son of a—"
Ryousuke's voice cracked as he stared at his surroundings. "Where the hell am I?"
He didn't have time to process the unfamiliar wooden walls before a flood of memories surged into his skull, churning through his brain like a blunt blade.
The Meiji Era. Rumors of man-eating demons lurking in the shadows of the night. A clandestine group of swordsmen known as the Demon Slayer Corps, dedicated to hunting them down.
This is... Demon Slayer? Are you kidding me?
Ryousuke wanted to wail. He wanted to throw a fit. Instead, he felt a crushing weight of regret.
I hadn't even spent those Primogems I spent months saving! The Hidden Leaf is left undefended! I didn't even get to delete my browser history!
The thought of someone—the authorities, a relative, anyone—cracking his phone and finding his "study materials" or those questionable mobile games made his blood run cold.
"My reputation is ruined!" he howled at the ceiling.
He had been a decent guy, a productive member of society who did his best to stay out of trouble. He hadn't even been hit by a truck; he'd simply gone to bed after a long night of gaming and woken up... here. It turned out that "death by overwork" wasn't just a myth.
The good news: Ryousuke knew the original story inside and out.
The bad news: He was already dying.
"Gah!"
A sharp, searing pain tore through his abdomen. His muscles went rigid, his body convulsing as he doubled over and retched a spray of crimson onto the floor.
The original owner of this body had been a sickly wretch on death's door. His parents had been devoured by demons, and he had only been spared by a stern-looking old man with a prosthetic leg and a cane.
"I'm already this pathetic... System, if you're there, quit hiding!" Ryousuke gasped through the pain.
Bzzzt—
A static-filled chime rang in his mind.
[Demon Slayer System Activated.]
[Host may obtain lifespan and cure ailments by slaying demons. Lifespan points may also be expended to master Breathing Styles and sword techniques.]
Ryousuke's lip twitched. "System."
[Yes?]
"How long do I have?"
[Congenital liver failure. Twelve months remaining, max. Tee-hee~]
"Don't 'tee-hee' me, you piece of junk!"
Ryousuke's fury flared. This was a joke. He was supposed to hunt demons with a body that could barely stand? He didn't even have a Nichirin Sword, and the System wanted him to play with his own life as currency?
"How am I supposed to kill anything like this?" Ryousuke snarled internally. "Am I supposed to kill them with kindness? Hope they feel bad enough to tan themselves in the sun?"
[Do not panic, Host. At least it is a liver issue, not a lung issue. With physical conditioning and Breathing Styles, you can mitigate the symptoms. You'll just die... slower.]
Ryousuke ground his teeth so hard he thought they might shatter. "You're useless! Who programmed you? I want to speak to a manager!"
The static buzzed again, then went silent. The System was playing dead.
He took a long minute to swallow the bitter pill of reality. There was no other choice. He had to train. He had to learn. If he didn't kill demons, he was a dead man walking.
"Ahem."
A deliberate cough echoed from the doorway, cutting through Ryousuke's internal rant. He looked up.
An old man stood at the entrance. He was short, but he carried an aura of immovable weight. His hair and beard were stark white, his expression etched with a habitual severity. Most striking was the jagged scar running beneath his left eye and the wooden peg-leg that supported his weight.
Kuwajima Jigoro. The former Roaring Hashira. The man who would eventually train Zenitsu Agatsuma and Kaigaku.
"Awake?" Jigoro asked. His voice held a trace of concern, though it was mostly buried under a layer of flinty discipline. "You have a stubborn soul, boy."
"Thank you for saving me, Elder," Ryousuke said, attempting to bow. His body betrayed him, his movements clumsy and strained.
"Hmph." Jigoro hobbled closer, his gaze sharp as a katana as it swept over Ryousuke. "That frame of yours... it's like rotted wood. A stiff breeze would snap you in half. You're weaker than an old man like me. Congenital liver failure and depleted vitality—it's a miracle you've breathed this long."
Ryousuke winced. Tell me something I don't know, old man.
"Born with it?" Jigoro asked.
"Yes."
"I see." Jigoro's brow furrowed. "The doctors in the Corps might be able to help you manage it. Buy you a little more time."
Ryousuke felt a hollow laugh bubbling in his chest. Based on his memories, they were about ten years out from the main story. Shinobu and Kanae were still children. The Butterfly Mansion didn't even exist yet.
Manage it? In this era? You didn't "manage" organ failure; you just waited for the lights to go out.
As for becoming a demon... he'd rather not. Muzan Kibutsuji was a toxic boss with no benefits and a high turnover rate. Even if Ryousuke offered to find the Blue Spider Lily in exchange for his life, Muzan would likely kill him the moment he got what he wanted.
The only path forward was the System.
The primal urge to survive washed away his hesitation. Jigoro watched the shifting emotions on the boy's face, likely preparing a speech about "cherishing his remaining days."
But Ryousuke moved first. He forced his shaking body upright and bowed at a sharp ninety-degree angle.
"Coach! I want to play basket—wait, wrong line."
He cleared his throat and started over, his voice trembling but firm.
"Master! I want to slay demons! Please, teach me!"