"Thank you for saving me. My name is Ryūjin Kaidō."
Nezuko: "Ryūjin Kaidō... what an unusual name!"
Tanjiro: "Nezuko, don't be rude!" He turned back quickly. "I apologize—my sister can be a bit blunt. Please don't take offense."
"None taken. Your sister's adorable. I like her." Kaidō's smile was genuine.
Watching Nezuko kneeling beside him, Kaidō couldn't help but reach out and gently pat her head, murmuring almost to himself, "If only my sister were here too... but I've already..."
The gesture caught Nezuko off guard—her face flushed red, though she didn't pull away.
Tanjiro's nose picked up a wave of melancholy emanating from Kaidō, but underneath it lay something else—something he couldn't quite identify or put into words.
"Sorry, I didn't mean to make things awkward." Kaidō withdrew his hand quickly.
"If you don't mind, you're welcome to stay with us for a while," Tanjuro Kamado said with a warm smile.
"Yes, please stay! The children seem to have taken quite a liking to you already," Kie added.
Takeo: "Yeah, big brother! Stay with us! You can play with us, and I want to hear your stories!"
Hanako: "Please stay! Your hair is so long and beautiful—can you teach me how to style mine like that?"
...
Kaidō looked at the family surrounding him, their voices overlapping with genuine warmth. Something deep in his chest loosened. "Thank you all—Tanjuro-san, Kie-san, Tanjiro, Nezuko, Hanako, Takeo, Shigeru, Rokuta. I'll be in your care for a while."
Despite their simple lifestyle, the Kamado family radiated warmth.
His thoughts drifted to his own mother and adoptive sister, to his best friend Hayato. How are they doing now?
...
Seven days passed living with the Kamado family. During that time, Kaidō maintained a careful routine—aside from daily life with the family, he carved out time each day to practice Dragon Breathing, steadily increasing his proficiency.
He often helped Tanjiro chop wood and make charcoal, occasionally joining him on trips down the mountain to sell their wares.
While Kaidō could easily give them money to improve their situation, he knew their humble, honest nature wouldn't allow them to accept it.
So instead, he helped with their work and sometimes brought back treats for Nezuko and the younger children after selling charcoal with Tanjiro.
When Kie tried to refuse, Kaidō simply said, "The children are still growing. Better food will help them develop properly."
Tanjiro: "Kaidō-san, you're not really that much older than me, are you?"
Kaidō: "I'm thirteen—two years older than you. Doesn't that make me your older brother?"
'If you knew my actual age from my previous life was twenty-five, I'd be your uncle, not your older brother.'
Thank god for the system creating a new body for him.
But that wasn't even the worst part. Why did the system have to shrink him when it reconstructed his body?
'In my previous life, I was at least five-foot-nine. Now? I'm stuck at barely five feet. I swear the system did this on purpose. System, you're on my list...'
System: [Host, I can hear you. Host has a thing for lolis.]
Kaidō: "..."
System: [Host collected numerous loli posters.]
Kaidō: "(ಠ_ಠ)"
System: [Host's computer contained...]
Kaidō: "You know what? This height is perfect. No need to change it. Besides, modifications always come with a price, so let's just leave it as is!"
System: [As long as Host is satisfied.]
Kaidō: "(¬_¬|||)"
Tanjiro: "Kaidō-san, are you alright? You look pale—are you feeling sick?"
"I'm fine, really. Just remembering something from the past. Don't worry about it—it's getting dark. We should head back. Nezuko and the others are probably waiting for us." Kaidō quickly changed the subject.
Though Tanjiro found the exchange odd, he didn't press further. The sky was indeed darkening, and once night fell, wild animals would emerge from the mountain forests to hunt. Better not to risk it. Without another word, he hurried to catch up with Kaidō.
.....
Time passed swiftly. Before long, Kaidō had been living with the Kamado family for half a month.
During this period, the system hadn't issued a single task or given any notifications—as if it had fallen dormant. But Kaidō knew better. The system was never that simple.
"Over the past two weeks, I've been practicing Dragon Breathing whenever I could. I've successfully developed two new forms."
Dragon Breathing, Fifth Form: Violent Tempest — Rapidly swing the blade forward, unleashing a barrage of sword strikes. The sheer brutality of consecutive slashes depends entirely on the user's strength and can generate anywhere from dozens to hundreds of blade projections.
"At my current level, I can unleash about fifty sword projections. If I stack it with the First Form, I can push it to nearly ninety."
Dragon Breathing, Sixth Form: Tornado Maelstrom — Area-of-effect attack. Spin rapidly with yourself as the center point, creating a vortex of blade energy through high-speed rotation. (Think of it like Yuzuru's technique from Date A Live.)
"According to the timeline, Tanjuro dies when Tanjiro turns twelve—roughly six months from now. The Final Selection on Mount Fujikasane happens once a year, which means I have less than five months left to prepare."
Kaidō's internal monologue took on a darker, more analytical tone.
"I know how the story is supposed to unfold, but if I intervene carelessly and alter the plot, I might trigger a butterfly effect—leading to an entirely different outcome."
His mind turned to the tragedy awaiting the Kamado family.
"One year after Tanjuro's death, the Kamado family is attacked by Muzan Kibutsuji. But I've always had doubts about that."
The question gnawed at him like an itch he couldn't scratch.
"Was it really Muzan who slaughtered Tanjiro's family? Given Muzan's cowardly, paranoid nature, would he truly risk attacking the Kamado household personally?"
The circumstances of their deaths had always struck Kaidō as strange.
When Tanjiro returned home, he found only corpses—no signs of consumption. Ordinary demons wouldn't leave bodies behind. They'd devour everything.
And why does everyone assume it was the Demon King just because Nezuko turned into a demon?
Muzan had no logical reason to target this specific family. He typically operated in bustling urban centers, not isolated mountain villages. If he were hunting down the inheritor of the Sun Breathing technique, he would have learned about it through his subordinates—yet not a single demon throughout the entire story ever mentioned Muzan being responsible for the massacre.
If revenge were his motive, he'd be searching for the wielder of the Hanafuda earrings. Given Muzan's paranoid nature, he'd only strike after confirming the location of the Sun Breathing user. Barging into the Kamado residence on a whim wasn't his style.
Furthermore, Kokushibo—Upper Rank One—had explicitly stated that he and Muzan had already eliminated all known descendants of Yoriichi Tsugikuni's breathing techniques. In Muzan's mind, there should have been no one left to take revenge against.
Another detail stood out: all the Kamado family members were left as whole corpses.
When Muzan killed—whether human or demon—he never left intact bodies. During the purge of the Lower Ranks, every demon except Enmu was obliterated without a trace. When a servant discovered Muzan wasn't human, that person was instantly reduced to pulp.
Why would such a violent, brutal entity leave every single victim as a whole corpse?
So who was the real culprit?
Whoever it was possessed the ability to create demons—meaning they had access to Muzan's blood, and not just a small amount. They had combat capabilities far beyond normal humans and could replicate the attack patterns of demons.
Who fits these criteria?
After eliminating Muzan as a suspect, Kaidō's mind sifted through the possibilities: the Twelve Kizuki, Tamayo, or—however absurd it seemed—the Demon Slayer Corps itself.
The Twelve Kizuki could be ruled out first. While they possessed the ability to create demons, they lacked motive. Creating demons required Muzan's explicit approval, and since Muzan remained unaware of Nezuko's existence, they were off the list.
Tamayo could also be eliminated. She had been turned into a demon by Muzan without her knowledge, devouring her own husband and children in the process. Her hatred for Muzan ran bone-deep. Had she not encountered Yoriichi Tsugikuni, she never would have escaped Muzan's control.
While Tamayo could transform humans into demons, she always asked for consent first—as she had with Yushiro. She was a demon fighting for humanity's sake. There was no way she'd slaughter an innocent family.
That left the third possibility.
The Demon Slayer Corps.
The very idea seemed ludicrous. Demon slayers and demons were supposed to be mortal enemies, sworn to destroy each other. But even if the probability was one in ten thousand, it wasn't impossible.
Because in Kaidō's eyes, the circumstances surrounding the Kamado family's deaths were far too suspicious to ignore.
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~# Every 300 Power Stones = Bonus Chapter!
~# Add to Library!