The fire had begun to die.
What remained of Rin's home crackled softly, embers glowing like fading stars. But inside that broken house, something far more dangerous was awakening.
Aiko's fingers twitched.
Rin felt it.
"Aiko…?" his voice trembled, but he didn't move away.
Her breathing grew uneven—sharp, unnatural. Then suddenly, her body arched upward as if pulled by invisible strings.
A low growl escaped her throat.
Not human.
The Demon Slayer stepped forward, his blade catching the faint light of the flames. His eyes were sharp now, focused.
"Move," he said.
Rin shook his head, placing himself firmly between them. "No! She's still my sister!"
"She won't be for long."
Aiko's head snapped toward them.
Her glowing eyes locked onto Rin.
For a moment—just a moment—there was recognition.
"…Bhai…?" she whispered weakly.
Hope surged inside Rin.
"You see?! She's still here!" he shouted. "She's fighting it!"
But the Demon Slayer didn't lower his sword.
"You don't understand," he said quietly. "That moment… that hesitation… it won't last."
As if proving his words true, Aiko's expression twisted in pain. Her hands clawed at the ground. Her teeth sharpened, lengthening into fangs.
Her voice broke into something monstrous.
"Hungry…"
Rin's heart shattered.
"No… Aiko… please…"
She lunged.
Fast.
Too fast.
The Demon Slayer moved instantly—his blade cutting through the air toward her neck.
"NO!" Rin screamed, throwing himself forward.
The blade stopped.
Just inches from Aiko's throat.
Time froze.
The Demon Slayer's arm trembled slightly… then he stepped back.
"…She didn't attack you to kill," he said slowly. "She hesitated."
Rin held Aiko tightly as she struggled, her body shaking violently.
"She's still human," Rin said, almost begging.
The Demon Slayer studied them both.
In all his years… he had never seen this.
A demon… holding back.
Finally, he sheathed his sword.
"This changes things," he muttered.
The night grew quieter, but the danger had not passed.
Rin sat outside the remains of his home, holding Aiko as she drifted in and out of consciousness. Sometimes she growled. Sometimes she cried like a normal girl.
It was terrifying.
"Why is this happening?" Rin asked.
The Demon Slayer stood nearby, watching the horizon.
"Demons are created when one of their leaders shares their blood," he explained. "That blood corrupts humans, turning them into creatures that crave flesh."
"Leaders…?"
"Yes. There are powerful demons who control others. The stronger the demon, the more humans they can turn."
Rin tightened his grip on Aiko. "Then we just have to find them… and stop them."
The Demon Slayer looked at him.
"That's not something a normal person can do."
Rin met his gaze.
"Then I won't stay normal."
Silence.
The wind passed through the trees, carrying the scent of ash.
"You're serious," the Demon Slayer said.
"Yes."
"…Even if it means killing your own sister someday?"
The question hit harder than any blade.
Rin looked down at Aiko. Her face looked peaceful for a moment—like she used to be.
"I won't let it come to that," he said.
The Demon Slayer sighed softly.
"My name is Kaito."
"Rin."
Kaito nodded. "If you truly want to protect her… then you need strength. Real strength."
Rin clenched his fists. "Teach me."
Dawn arrived slowly.
For demons, sunlight meant death.
As the first rays touched the forest, Aiko screamed.
Her skin began to burn.
"Cover her!" Kaito shouted.
Rin quickly wrapped her in a thick cloth, shielding her from the light. The burning stopped, but her breathing remained weak.
Kaito's expression grew serious.
"Another weakness," he said. "Demons cannot survive sunlight. Even the strongest fear it."
Rin nodded, memorizing every word.
"Cutting off their heads kills them… and sunlight destroys them," he repeated.
"Correct."
Rin looked toward the rising sun.
"So that's how we fight back."
Days passed.
Rin and Aiko traveled with Kaito through forests and mountains. During the day, Aiko remained hidden. At night, she walked beside them—silent, struggling.
Sometimes she lost control.
Once, she nearly attacked a traveler.
Rin stopped her.
Barely.
Each time, it became harder.
"You see?" Kaito said one night. "This is the reality."
Rin didn't respond.
He just trained harder.
Kaito taught him everything—
How to hold a sword.
How to breathe properly.
How to listen… to silence.
"Your body is weak," Kaito said during training. "But your will… is strong. That's why you're still alive."
Rin swung his blade again and again, his hands bleeding.
"I won't stop."
One night, everything changed.
They were resting near a quiet village when a scream echoed through the darkness.
Kaito's eyes snapped open.
"A demon."
Rin stood instantly.
"Let's go."
They ran.
The scene was chaos.
A massive demon towered over the villagers, its body twisted and monstrous. Its arms stretched unnaturally long, smashing through walls.
"This one's strong," Kaito said.
The demon laughed.
"More food… more blood…"
Rin felt fear.
But he didn't run.
"Stay back," Kaito ordered, drawing his blade.
But Rin stepped forward.
"No."
Kaito frowned. "You'll die."
"Then I'll learn."
Before Kaito could stop him, Rin charged.
The demon noticed.
"A human… brave or stupid?"
It swung its arm.
Rin barely dodged, the ground cracking where he had stood.
His heart raced.
Too fast… too strong…
But he remembered Kaito's words.
Breathe.
Rin steadied himself.
Inhale.
Exhale.
The world slowed.
The demon attacked again.
This time, Rin moved differently.
He slipped past the strike and swung his blade—
But it wasn't enough.
The demon grabbed him.
"Got you."
Rin struggled as the creature lifted him into the air.
"RIN!" Kaito shouted.
But before the demon could crush him—
A blur moved.
Aiko.
She slammed into the demon, knocking it back.
Rin fell to the ground, gasping.
"Aiko…?"
Her eyes glowed brighter than ever.
But this time…
She wasn't attacking humans.
She stood in front of Rin.
Protecting him.
The demon growled. "Another one of us…?"
Aiko let out a fierce scream and attacked.
Kaito stared in shock.
"She's… fighting a demon?"
Rin slowly stood, gripping his sword.
"Aiko… thank you…"
He turned to Kaito.
"Let's finish this."
Kaito nodded.
Side by side, they charged.
The battle was fierce.
Steel clashed against flesh.
The demon roared, attacking wildly—but now, it was outnumbered.
Rin saw his chance.
He focused.
Breathed.
Moved.
And with everything he had—
He swung.
The blade cut clean through the demon's neck.
Silence.
The body collapsed.
Ash scattered into the wind.
Rin dropped to his knees, breathing heavily.
"I… did it…"
Kaito looked at him with something new in his eyes.
Respect.
Aiko stood nearby, her body trembling—but she didn't attack.
Not this time.
That night marked the beginning of something greater.
A human.
A demon.
And a slayer.
Walking the same path.
But far away… deep in the shadows…
A pair of glowing eyes opened.
"So… a demon who resists… and a human who fights…"
A voice echoed in the darkness.
"Interesting."
The true leaders of demons had taken notice.
And they were coming.