The wooden walls of the Infinite Fortress trembled violently.
The room’s structure, manipulated by Nakime’s Blood Demon Art, continued to shift and twist, creating a seemingly endless vertical labyrinth.
In one corner of the floating wooden dojo, thick dust swirled together with the heavy stench of blood.
“Huff… huff…”
Thick, dark-red fluid dripped from Tanjiro’s temple.
The blood flowed past his left eyelid, burning his vision and painting half the world in a deep crimson.
Tanjiro’s fingers trembled violently over the wrapped hilt of his Nichirin sword.
Every muscle in his arm was taut, convulsing from overwhelming exhaustion.
*Move… Please, just hold on a little longer!*
Tanjiro closed his eyes for a split second, roughly wiping the blood from his face with his shoulder, then forced her eyelids open wide once more.
At the far end of the room stood a solitary silhouette wearing an ornate, ancient-patterned kimono.
A night wind that came from nowhere gently fluttered the edges of the outer robe.
Rin Tsugikuni.
A living legend from the Sengoku Era, whose name was written in blood across the records of the Demon Slayer Corps.
The younger sibling of Yoriichi Tsugikuni, the creator of the first Breathing Style.
Now she stood there, no longer human.
A pair of cruel, glowing eyes marked her as one of the Upper Rank Twelve Kizuki.
The wooden dojo floor around them had been destroyed.
Shards of broken blades and torn black uniforms lay scattered across puddles of blood.
Tanjiro recognized several faces lying stiffly in the corners.
They were his comrades—senior demon slayers who had exchanged greetings with him just hours ago.
Rin’s footsteps sounded eerily light as she glided across the blood-soaked tatami.
Her long blade caught the torchlight, leaving behind cold, deadly glints.
“Haah!”
Tanjiro gripped his sword hilt tighter, stomping his right foot down so hard the wooden plank beneath it cracked.
Tears mixed with blood streamed down his cheeks as he lunged forward, ignoring the stabbing pain in his ribs.
His black sword swung, slicing through the air with the last of his strength.
***
Hundreds of years before that bloody night, the sun blazed fiercely above the Tsugikuni clan residence.
Beams of sunlight pierced the gaps in the long wooden corridor.
The sound of small, bare feet pattered quickly, creating a rhythmic beat along the rear courtyard walkway.
Rin Tsugikuni stopped right in front of a sliding door tucked away in the quietest corner.
Her small head turned left and right.
The corners of her eyes checked for any passing servant or guard silhouettes in the rock garden.
Once she confirmed it was safe, her tiny fingers slowly pushed open the low wooden door.
She crouched low and slipped into the silent room.
“Big Brother Yoriichi! Look, this is the new hairpin Mother made for me!”
The air inside the room felt cold and damp.
On a simple wooden bed without thick bedding, a boy in coarse clothing slowly shifted his position.
Yoriichi woke with slow movements and turned his body toward the door.
His gaze was pure, yet it carried no emotion typical of children his age.
His long, deep-red hair was loosely tied, and a red mark resembling blazing flames stood out clearly on his left forehead.
He was Yoriichi Tsugikuni, Rin’s older twin brother.
To Rin, this world was an incredible second chance.
The memories of her previous life as a frail girl who spent her final days bedridden in a hospital still clung strongly in her mind.
In this new life, she had been reborn in the womb of the graceful noblewoman Akane.
Her father was a powerful daimyo who ruled the fertile Tsugikuni territory.
But that peace had a terrifying dark crack.
The birth of twins in the samurai era was considered a curse that would bring bloodshed in the future.
Coupled with the strange mark on Yoriichi’s forehead as a baby, their father had nearly ended the child’s life with his own sword.
Only Akane’s tight embrace and hysterical cries had stopped the katana that night.
A cruel agreement was made.
Yoriichi would be allowed to live only until the age of ten, after which he would be sent to a remote temple to become a monk.
As a result, Yoriichi was treated worse than the servants of the household.
Michikatsu received the status of legitimate heir to the clan, while Rin grew up as the cherished youngest child.
Yoriichi was confined to this rundown room, without education, without proper clothes, and strictly forbidden from stepping into the main courtyard.
That was why Rin often sneaked into this secluded rear corner.
Sometimes, Michikatsu would secretly join her, bringing old books or brushes so they could study together.
“Big Brother Yoriichi, look at this.”
Rin knelt on the thin tatami right beside her brother.
She reached up and pulled the emerald-green jade hairpin from her small bun, then placed it in Yoriichi’s palm.
“Mother said these three leaves represent the three of us.”
Rin’s index finger gently touched the delicate carving on the jade.
“The leaf in the middle is me. The two leaves on the sides are Big Brother Michikatsu and Big Brother Yoriichi.”
Rin looked into her brother’s calm, drooping eyes.
“Mother told me that even if one day my two brothers must walk separate paths, I have to stand in the middle and hold both your hands. As long as we stay together, our clan will never fall apart.”
Rin tilted her head, waiting for a response that didn’t come.
Yoriichi stared at the jade hairpin for a long moment.
Slowly, he lifted his head.
The corners of his lips rose into a faint, thin line, accompanied by a very subtle nod.
“Ah! I almost forgot! There’s one more!”
Rin reached into the loose sleeve of her kimono.
A pair of wooden earrings with a blazing red sun motif now swayed between her fingers.
“These sun earrings are for you, Big Brother Yoriichi. Mother made them herself.”
Rin’s small hand gently pulled her brother’s stiff fingers and carefully placed the earrings in his palm.
“Mother said there’s a prayer she offered to Amaterasu Omikami every night inside these earrings. They will protect you from all harm throughout your life.”
Rin quickly stood up, brushing the dust off her kimono, then held out her hand toward Yoriichi.
“Come on, Big Brother Yoriichi. Let’s go outside. Father left at dawn to inspect the city territory. Mother asked me to bring you to the dining hall for breakfast together.”
From outside—specifically from the main training grounds—sudden sounds of heavy footsteps and loud wooden impacts echoed.
“Hah! Drink! One more time!”
“Magnificent! Excellent defense, Young Master Michikatsu! Please continue!”
Yoriichi, who had just been about to take Rin’s hand, suddenly stopped.
*Big Brother Michikatsu’s voice?*
Yoriichi’s ears twitched faintly.
His flat eyes shifted toward the tightly closed wooden window.
“What is… Big Brother doing?”