Chapter Ten: The Beginning of the Journey!
『RYON』
Yoo—enjoy the chapter!
The air inside the small wooden cabin froze. The silence was so heavy that the sound of burning wood in the hearth felt like gunshots.
Yukihara Rin—the "prodigy child" and a player who knew the secrets of this world—stood there with his Nichirin sword half-drawn, an unreadable expression on his face. In front of him, Kamado Tanjiro spread his arms like a human shield to protect a demon, while Urokodaki Sakonji calmly sipped his tea with irritating composure.
"I'm… an idiot," Rin screamed in his mind as he struggled to maintain his outward mask of seriousness.
How did he forget? How did such an obvious piece of information slip his mind?
"Of course Tanjiro is here! I calculated the dates and knew the massacre had already happened. Where did I expect the protagonist to be—Hawaii?"
Rin scolded himself harshly. It seemed that overusing "Thunder Breathing" all the way from Mount Fujikasane to this place had affected his brain chemistry. The insane speed at which he covered the distance didn't just drain his body—it also muddled his short-term memory. The excess oxygen and electricity surging through his veins made him focus on the "objective" and forget the "context."
"Rin," Urokodaki's calm voice cut through his tangled thoughts. "Lower your sword. And breathe."
Rin blinked and returned to reality. He looked at Tanjiro. The red-haired boy's eyes darted between Rin and Urokodaki, clear confusion on his face. Tanjiro's scent wasn't fear for himself, but fear mixed with confusion: why was this child pointing a sword at them? Was he an enemy?
Rin exhaled slowly, allowing the tension to leave his taut muscles (which had been ready to sever Nezuko's neck in a fraction of a second if not for reason).
He sheathed his sword with a smooth, silent motion. Click.
"I apologize," Rin said, forcing his voice to sound as natural as possible, ignoring the internal embarrassment gnawing at him. "I traveled a long distance at high speed… it seems my senses were overstimulated."
Rin sat in the opposite corner, placing his sword beside him as a sign of goodwill, while keeping his emerald eyes fixed on Nezuko with feigned caution. He had to play the role of a "rookie slayer who knows nothing" convincingly. It would be far too suspicious to say: Oh yes, this is Nezuko, the demon who will later conquer the sun—don't worry.
"Sit down, Tanjiro," Urokodaki gestured to his new student. "This is Yukihara Rin. My student who just graduated from the Final Selection."
Tanjiro's eyes widened, his confusion instantly turning into admiration. "You graduated? At this age? That's amazing!"
Tanjiro smiled—that bright smile capable of melting ice—and bowed respectfully. "I'm Kamado Tanjiro. And this is my younger sister, Nezuko. It's a pleasure to meet you, Yukihara-san."
"Just Yukihara," Rin replied curtly. "So… what's the story with the demon?"
Tanjiro began telling his story—the one Rin had watched hundreds of times in the anime and read in the manga. About selling charcoal, returning late, the stench of blood that greeted him, the massacre that took his family, and Nezuko's transformation.
Rin listened in silence, his eyes fixed on the cup of tea Urokodaki had given him.
Even though he knew the story, hearing it directly from its owner, seeing the living pain in Tanjiro's eyes, and smelling the deep sorrow radiating from him… was different.
"This isn't an anime," Rin reminded himself again. "This is these people's reality."
When Tanjiro finished, a heavy silence filled the room.
Rin sighed deeply and raised his head. "I understand. You're seeking a way to turn her human again."
"Yes!" Tanjiro replied, his enthusiasm mixed with despair. "Urokodaki-san told me I might find a way by fighting powerful demons—or Kibutsuji Muzan himself… and other demons who may have special blood. I'll do anything for her!"
Rin nodded. "I wish you luck, Kamado."
While thinking, "Right—Tanjiro hasn't met Muzan yet… he hasn't felt his power and terror yet!"
The atmosphere shifted slightly, and Tanjiro, with his usual kindness, tried to change the heavy topic.
"Yukihara-kun… if this isn't rude," Tanjiro began hesitantly. "You look younger than me—maybe ten? How… how did you become a Demon Slayer? And how do you possess this kind of strength? Your scent… it's different from anyone I've met. It's unique."
Rin placed the cup on the floor and leaned his back against the wooden wall. This was the moment he had to weave his story—the one that justified his illogical strength without revealing his secret as a reincarnator.
"I started at five," Rin said calmly, his eyes fixed on the hearth's flames.
"Five?!" Tanjiro gasped.
"Yes. I didn't know about demons back then. I was just a child living in a mountain village with my mother and sister. All I wanted was to be strong enough to protect them. There was no drive for revenge, no tragedy… just a pure desire for strength."
Rin began recounting the "modified version" of his life. He told him how he trained obsessively, how he learned judo and kendo, and how he began competing in local tournaments.
"They called me the 'Martial Arts Demon' or the 'Prodigy Child,'" Rin said with a faint, ironic smile. "I earned a lot of money from prizes. I took my family and moved to Akasaka City. I thought money and physical strength would protect us."
Rin paused for a moment, adding dramatic effect (since he liked drama).
"Then I encountered one."
Tanjiro held his breath.
"One night, a demon attacked our new home. While my family was asleep… He wasn't very strong by Corps standards, but he was a nightmare for a child with a wooden sword. I was helpless… or almost."
Here, he had to lie smartly.
"I fought with everything I had. I broke his bones, threw him off the balcony, and used every trick I knew. I couldn't kill him, but I managed to delay him. The fight lasted for hours, until…"
Rin raised his hand and opened it as if grasping sunlight.
"Until the sun rose. And the moment the light touched him… he burned. He vanished as if he never existed."
"Sunlight…" Tanjiro murmured, engraving the information into his mind.
"Yes. I didn't know then that the sun was their weakness. I thought it was a miracle," Rin lied smoothly. "That day, I met a Demon Slayer who arrived late. He told me about the Corps and the nature of these creatures. That's when I realized that protecting my family had been pure luck. If I truly wanted to protect them, I had to join the Corps."
Rin looked at Tanjiro, his emerald eyes shining with seriousness.
"My mother, Yukihara Yumi, always told me one thing…"
Rin quoted the famous line—not from the Marvel universe this time, but attributing it to his mother to give it emotional weight.
"With great power comes great responsibility. The strong are born to bear the burdens of the weak, not to rule over them."
Rin recalled Rengoku Kyojuro's mother—that great woman who instilled the same principle in her son, the Hashira.
"I feel I agree with this principle a lot," Rin thought. "Maybe if I meet Rengoku, we'll become close friends. We both love food, and we both carry the philosophy of protecting the weak… though I also like protecting myself."
Tanjiro looked at Rin with immense admiration, tears glistening in his eyes. "That… that's truly wonderful! Your mother is a wise woman, Yukihara-kun! And you're amazing for following in her footsteps!"
"Alright, don't exaggerate," Rin waved his hand with feigned shyness, though he was enjoying the protagonist's praise.
Urokodaki interrupted the moment with his stern voice, addressing Tanjiro.
"Don't be deceived by his gentle appearance or moving words, Tanjiro."
Both of them looked at the masked old man.
Urokodaki pointed toward Rin. "When this boy entered through the window earlier… if he hadn't hesitated for a fraction of a second upon seeing me sitting peacefully, your sister's head would be rolling on the ground right now."
Tanjiro's face went pale. He looked at Rin in terror, then at Nezuko, then back at Rin.
"He wasn't joking," Urokodaki continued coldly. "His speed, his judgment, his sword—all are honed for killing. He is a drawn blade, and you should be grateful that its edge stopped at the last moment."
Rin felt a bit embarrassed. "Master, there's no need to scare the boy…"
"I'm not scaring him. I'm teaching him reality," Urokodaki replied. "Your goal is to protect your sister, Tanjiro? Then know that there are people like Rin—stronger than him, even—whose sole mission is to kill beings like your sister without hesitation. If you want to protect her, you must become stronger than all of them."
The words were harsh, but necessary. A new resolve ignited in Tanjiro's eyes.
…
The next morning.
Dawn had barely begun to pierce the darkness of night, and the air on Mount Sagiri was so cold that breath instantly turned into icy crystals.
"Wake up!"
Urokodaki's voice was like a military alarm.
The three of them went out into the courtyard. Tanjiro wore simple training clothes, while Rin wore wide black hakama and his haori—but underneath, he was wearing something else.
"Tanjiro, your task today is to descend the mountain and return before noon," Urokodaki ordered. "The traps have been reset."
"Yes, sir!" Tanjiro dashed off enthusiastically, though he tripped in the first three steps.
Then Urokodaki turned to Rin.
"As for you… now that you're Mizunoto, ordinary training won't benefit you."
Urokodaki tossed a heavy cloth bag toward Rin.
"Put these on."
Rin opened the bag. They were wrist and ankle weights. They looked like ordinary cloth, but when Rin lifted them, he felt an unnatural heaviness.
"High-density iron," Rin analyzed instantly. "Each piece weighs about 20 kilograms."
Rin put them on without complaint—an extra 80 kilograms on his small body.
"And now what? Do I go down the mountain too?" Rin asked, hopping in place to test his new balance.
"Yes," Urokodaki said, drawing a long wooden sword. "But the traps won't be your only problem."
Urokodaki vanished from his spot.
Suddenly, Rin felt genuine killing intent behind him.
"The problem will be me."
"Damn it!"
Rin leaped sideways at the last moment as Urokodaki's wooden sword passed through where his head had been, shattering a small rock.
"A chase? I love it!" Rin grinned savagely and sprinted down the mountain.
While Tanjiro struggled with pits, ropes, and flying knives—shouting "Trap scent!" every two minutes…
The scene on the other side of the mountain looked like a horror movie of a completely different level.
Rin leaped between trees, the weights dragging him down, while a mad "tengu" chased him, swinging a wooden sword at Hashira-level speed.
"Faster! You're slow!" Urokodaki shouted as he delivered a strike that nearly broke Rin's ribs.
"I'm trying not to die here!" Rin retorted, using a tree trunk as a pivot to perform a backflip, narrowly avoiding the strike and kicking Urokodaki's face (which the old man easily blocked with his hand).
The gap in their training levels was both absurd and terrifying.
When Tanjiro returned at noon, he was covered in mud and bruises, panting as if he were about to die.
"I… I'm back…" Tanjiro collapsed face-first.
A minute later, Rin arrived.
His clothes were torn, sweat poured off him like a waterfall, but his breathing was eerily steady thanks to "Storm Breathing" (which he was now using for recovery).
"Are you done?" Urokodaki asked as he stood by the door, as if he hadn't been running through the mountain moments ago.
"Tanjiro, rest and meditate. Rin… to the waterfall."
While Tanjiro tried to learn how to grip a sword and swing it 500 times…
Rin stood beneath an icy waterfall, bare-chested, the weights still on. The water hammered his body with tremendous force as he kept his eyes closed, mentally practicing "Water Breathing" forms and trying to merge them with "Thunder Breathing" to increase the stability of "Storm Breathing."
[Storm Breathing Stability Rate: 96%… 97%…]
Tanjiro watched Rin from afar while swinging his sword.
"Rin-san is amazing…" Tanjiro murmured. "He trains ten times harder than I do, even though he's younger and already stronger than me. I can't give up! I have to work even harder!"
"998… 999… 1000!" Tanjiro shouted enthusiastically. "I'll do 500 more!"
Rin smiled inwardly as he heard Tanjiro. "That's the protagonist's effect. He inspires himself. But…"
Rin opened his emerald eyes beneath the crashing water.
"I'm not playing the hero's game here. I'm playing the survival game."
…
The days passed similarly—but densely.
Every day was a repetition of hell.
Morning: a death race with Urokodaki.
Noon: strength and endurance training under the waterfall or by carrying massive boulders (under Tanjiro's shocked gaze).
Evening: meditation sessions to merge breathing styles, and Rin's (mostly failed) attempts to teach Tanjiro some modern scientific concepts about muscles and breathing—which Tanjiro interpreted in his own way: "The scent of oxygen!"
Rin and Tanjiro grew close in a strange way. Tanjiro saw Rin as a strict yet inspiring "senpai" (experienced senior). Rin saw Tanjiro as a kind "kohai" (junior) who needed protection… but not pampering.
On the fifteenth day.
Rin stood before Urokodaki in the morning.
He wasn't wearing the weights today. He wore his official Corps uniform, and the gleaming black Nichirin sword (which had arrived two days after the mourning).
"Time's up," Rin said.
Urokodaki looked at him. "Are you ready?"
"More than ever."
Rin turned to Tanjiro, who was looking at him sadly as they parted.
"Tanjiro," Rin said, tossing him something small.
Tanjiro caught it. It was a jar of medicinal ointment Rin had skillfully made (handcrafted).
"This is for cuts and bruises. Your recovery speed will improve. Don't die. Don't give up. I'll be waiting for you at the summit."
"Thank you, Yukihara-kun!" Tanjiro bowed deeply. "I promise—I'll catch up to you!"
"Alright, stop that. From now on, when we meet again, call me by my name… Rin!"
Rin smiled and turned to face the descending path of the mountain.
Fifteen days of additional training were enough to polish "Storm Breathing" to 100%.
[Status]
[Name: Yukihara Rin
Gender: Human / Male
Age: 10
Level: 45
Strength: 122
Agility: 133
Endurance: 128
Intelligence: 156
Spirit: 189]
This was the extent of Rin's current power.
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