Chapter 1 — Blade Name: Ryūjin Jakka!
Ken was frozen awake.
When he opened his eyes, he found himself lying inside a dilapidated shack. Outside was a world of ice and snow; the piled-up drifts had nearly spilled into the shelter.
He glanced at his frail body—ribs so thin they looked ready to tear through skin, bony fingers wrapped in a thin layer of flesh, and dry, emaciated limbs—and immediately understood his situation.
"Damn it… fine, I transmigrated… but could I at least get a full meal? Starting on nightmare difficulty, huh?!"
After muttering a few curses under his breath, Ken fell silent to conserve his strength.
[The Strongest Shinigami System is binding… Binding in progress…]
Just as Ken was calculating how much longer he had before he starved to death, an unfamiliar voice echoed in his mind.
"A s-system?!" Ken froze.
"Hold on. In my half-dead state, what good is binding the Strongest Shinigami System? Can you switch to one that actually saves lives?!" he roared internally.
With the double debuffs of "Hunger" and "Cold" stacked on him, surviving the day itself was questionable!
And you bind me to a Strongest Shinigami System—what the hell is that supposed to do?!
Can I eat it?
Wait… Shinigami system…
Ken seemed to realize something.
Oh hell, system—you're malicious as hell!
[Ding! It has been detected that the host's current world is incompatible with the system. Initiating rebinding. The new system will perfectly integrate with the rules of the main world. Wishing you a pleasant life!]
Pleasant my ass, system!
[The Strongest Shinigami System (Local Version) is binding… Binding in progress…]
Ken: "..."
I swear I bought a fake system last year.
[Binding successful! As the host's "Foul Language" has reached Level 10, you are specially rewarded with the "Birdsong and Blossoms Gift Pack." Would you like to claim it?]
"System, did you just insult me again?!"
[…Would you like to claim it?]
"Claim!"
[You have obtained: Advanced Draw Opportunity ×1, Water Breathing. Would you like to use it immediately?]
"That's it?!"
[...]
The air suddenly grew very quiet.
"…Aren't you going to ask whether I want to use the draw?"
He can't even decline. Where's he's human rights?
[Would you like to use the draw opportunity?]
Ken was now certain—this system's quality was seriously questionable.
"Use it!"
In the next instant, a golden lottery drum appeared before his eyes, filled with beads of various colors.
[Advanced Draw: Chance to obtain Captain-level Zanpakutō (Local Version · Special Nichirin Blade), High-level Kidō (Local Version · Special Blood Demon Art), Zanpakutō Bankai, Zanpakutō Shikai… and other rewards.]
The voice fell silent as the golden drum began spinning wildly.
At the same time, Ken realized which world he had transmigrated into…
The world of Demon Slayer!
A world where successfully inviting Muzan out to bask in the sunlight would trigger a good ending!
But that hardly mattered to Ken. At this rate, he wouldn't survive the day. There was no way he'd draw a full-course meal from that drum!
Clack!
A fiery-red bead dropped from the drum and landed in the tray below.
[Congratulations to the host for obtaining Zanpakutō: Ryūjin… An error has occurred in the draw program. Initiating redraw—]
"System, read the last two words! Ryūjin what? Do you want me to teach you how to pronounce them?"
"With your level of education, you dare go out and call yourself a system? Aren't you embarrassed? Why don't you piss in a mirror and take a good look at yourself! Trying to redraw? Why don't you reinstall yourself while you're at it?"
[…Congratulations to the host for obtaining Zanpakutō: Ryūjin Jakka!]
At that moment, Ken felt the will to live return to him.
"I think I can still be saved. I can't die yet! I haven't invited Muzan to sunbathe!"
Immediately afterward, an ordinary-looking katana appeared in his hands—a deep purple hilt, an oval guard, and a brown scabbard.
"Hahaha… hahaha…" Ken laughed weakly, barely able to muster the breath.
"I'm going to live!" The fire of life began blazing fiercely within him.
[Distributing reward: Water Breathing Technique!]
As the words fell, a flood of information regarding Water Breathing poured into Ken's mind.
At the same time, his body began breathing rhythmically—precisely in accordance with Water Breathing.
Ken knew the system was helping him master it. He immediately cleared his mind of all distractions, keeping his heart as calm as still water.
Feeling the rhythm of Water Breathing, Ken slowly began attempting to control the tempo on his own…
Breathing Techniques were methods used by members of the Demon Slayer Corps to enhance their physical abilities in order to fight demons, whose bodies far surpassed those of humans. Collectively, they were known as "Total Concentration Breathing."
Their primary function was to strengthen heart and lung capacity, enabling the blood to absorb massive amounts of oxygen in a short time. This dramatically increased physical ability in an instant, temporarily granting strength comparable to that of demons.
But with Ken's current condition, even using Water Breathing would only allow him to move normally. Any slightly intense activity was out of the question.
Half an hour later…
Still lying in the shack, Ken had, despite some clumsiness, successfully grasped Water Breathing.
If the current Water Hashira, Giyu Tomioka, or the former Water Hashira, Sakonji Urokodaki, saw that Ken had gone from zero to mastery in just half an hour, they might seriously question their lives—and whether they deserved the title of Water Hashira.
Even though Water Breathing was considered the gentlest and easiest to learn among all Breathing Styles, mastering it in half an hour was downright outrageous.
Of course, Ken had only managed it so quickly thanks to the system's assistance.
Without the system actively guiding his lungs and heart to match the breathing rhythm, mastering Water Breathing on his own would have taken months—assuming he even had decent talent.
"Huff… huff… huff…"
Squeezing what little strength he could from his frail body, Ken crawled out of the shack, gripping Ryūjin Jakka as he stepped into the thick snow.
......
On the street, a boy of about fourteen or fifteen was walking along, calling out as he sold charcoal. Strapped to his back was a basket nearly half his height, filled with large chunks of coal.
Even for an average adult man, carrying such a load would be strenuous.
Yet the boy looked completely at ease, as if long accustomed to it.
"You're selling charcoal so early today. Tanjiro really is a hardworking child."
"You flatter me. Do you still have enough charcoal at home?"
"We do. But having extra doesn't hurt—just in case heavy snow blocks the mountain road one day."
"Then I'll take another ten pounds."
"Of course! Thank you very much!"
"Tanjiro, could you help carry these goods up to the second floor?"
"Please leave it to me!"
"You're such a help. Come have some rice balls before you go!"
"Thank you for your hospitality!"
"Ri-rice balls?" Ken turned toward the source of the voice. White, plump rice balls seemed to appear before his eyes.
"Rice balls!" He reached out to grab them—
His hand grasped nothing but air. Weakness overtook him, and he collapsed into the snow, losing consciousness.
"...Are you alright?!"