A streak of green light shot through the warped space of the Infinity Castle.
Shinichi pushed his speed to the absolute limit.
The surrounding scenery blurred past him—inverted pavilions, twisted corridors, floating wooden planks, and a bottomless void.
As he advanced, the ominous premonition clinging to his heart grew heavier, like a cancer gnawing at his bones.
'Something is terribly wrong. What lies ahead?'
From the moment he entered this area, Shinichi had sensed an indescribable strangeness.
Even the air seemed to thicken, as if an invisible force were crushing his body.
He effortlessly dispatched several demons blocking his path or lurking in the shadows.
Yet, strangely, these demons showed little aggression.
Most simply stood dumbly in his way, as if their souls had been ripped from their bodies.
"What... is this place?" Shinichi muttered, tightening his grip on his Nichirin Blade.
Activating his Breathing Style to its fullest, Shinichi's senses sharpened, detecting a profound anomaly.
The life force in the area ahead was being twisted and devoured in a deeply unnatural way.
Even the soulless demons had auras so faint they were barely perceptible.
If he had to describe it, Shinichi felt the region ahead resembled the mythical underworld—Yomi!
The oppressive force in the air... it was the aura of Yomi!
At this realization, alarm bells screamed in Shinichi's mind.
He quickened his pace, fearing what horrors might unfold if this continued unchecked.
Just as his focus reached its peak, his senses strained to perceive every detail around him, a silver crescent-shaped blade of energy erupted from the shadows to his side without warning!
The attack was astonishingly fast, carrying a sharpness that seemed capable of slicing through anything.
Judging by its aura alone, this single strike could effortlessly cleave through hardened steel!
Anyone else might have been caught off guard, but Shinichi had been on high alert for some time.
"Breath of the Forest, Fourth Form: Dandelion Dance!"
At the critical moment, Shinichi's body reacted instinctively.
Like a dandelion seed scattering in the wind, he twisted and sidestepped at an impossible angle, narrowly evading the crescent blade.
BOOM!!!
The blade energy grazed past Shinichi's body and slammed viciously into the wall behind him, cleaving through the thick wooden partition and several layers of structure beyond.
A shower of splinters erupted into the air!
Shinichi landed, debris flying behind him. He held his Nichirin Blade horizontally, its surface pulsing wildly with emerald-green light.
Gripping the hilt tightly, he stared toward the direction the attack had come from.
"Who's there?"
From the darkness, a figure slowly emerged.
A tall, slender frame.
A twisted, deformed blade. Six cold, menacing eyes. And an ancient, purple samurai battle robe.
Upper Rank One—Kokushibo.
'So it's him.' Shinichi wasn't surprised.
After the deaths of Akaza and Doma, Kokushibo was the only Upper Rank left.
It was only natural that he would be the one to block Shinichi's path.
Kokushibo, in contrast, remained as impassive as ever.
His six eyes stared coldly at Shinichi, as if observing an ant that had trespassed into forbidden territory.
"Forest Hashira, Moriki Shinichi," Kokushibo's voice was deep and chilling. "I have heard of you. Even Akaza and Doma fell to your blade. Your strength is worthy of my personal attention."
"Right back at you," Shinichi retorted, his tone dripping with contempt. "I'm also looking forward to using this Nichirin Blade to sever the heads of the top three Upper Ranks. And now, you're the only one left!"
Despite his scornful words, Shinichi's eyes held no trace of underestimation.
Instead, his gaze was grave, his focus sharper and more vigilant than ever before.
Standing before him was Upper Rank One—the strongest demon second only to the Demon King, Kibutsuji Muzan himself.
The grievous injuries Gyomei and the Tokito brothers had sustained earlier were proof enough of this demon's terrifying power.
"Kokushibo, weren't you teleported away?" Shinichi taunted during the standoff. "I thought you'd take the chance to flee. After all, it's only natural for a demon to fear death, isn't it?"
He didn't know if the jab would provoke Kokushibo into revealing an opening, but it was worth a try.
"Fear death?" A flicker of emotion rippled through Kokushibo's six eyes. "When you have lived for hundreds, even thousands of years, you will understand. Fearing death is an instinct shared by all living beings. There is nothing inherently wrong with pursuing eternal life and ultimate strength!"
Kokushibo slowly raised his Deformed Blade, the energy of his Breath of the Moon beginning to gather.
"And one more thing..." Kokushibo's voice took on an eerie tone. "You're not just fighting me."
The moment he finished speaking, Shinichi's pupils constricted!
From the deep shadows behind Kokushibo, another figure slowly emerged.
The figure stood shoulder-to-shoulder with Kokushibo, equally tall and slender, clad in the same ancient red samurai armor, and wielding a Nichirin Blade of antique design.
Most strikingly, his dark red hair was nearly identical to Kokushibo's—as was his face!
When the figure fully stepped out of the shadows and into the faint light, Shinichi's heart nearly stopped.
That face, that posture, those identical strands of dark red hair!
'Who is that?' The figure's indifferent gaze merely swept over Shinichi, yet it sent a chill through his entire body.
A terrifying pressure crashed down on him, and for a fleeting moment, Shinichi felt as if he were staring directly into the sun.
'Shhh!'
Under the weight of the figure's gaze, Shinichi involuntarily took half a step back.
'So strong! Just standing there makes me feel like he's unbeatable!'
Suddenly, as Shinichi stared at the figure's attire, legends and records flooded his mind—one after another.
Whether from the historical annals of the Demon Slayer Corps, the inherited chronicles of the Moriki Family, or even the words of Lady Tamayo, who had lived for centuries, all spoke of one man.
A man so powerful that even the Demon King Muzan would never forget him.
'The Strongest Swordsman—Tsugikuni Yoriichi!'
'Could it really be him?!' Shinichi thought, his gaze fixed on the man standing beside Kokushibo.
Shinichi wasn't the only one in shock.
Kokushibo himself was seething with revulsion at the figure beside him.
If not for his extreme self-control, his Deformed Blade would have struck that infuriating face long before Shinichi could even react.
But the unshakable control flowing through his bloodline froze Kokushibo's impulse, forcing him to stand alongside Yoriichi and face Shinichi.
"A... fascinating swordsmanship," Yoriichi spoke, his voice flat and devoid of praise, as if making a casual observation.
He raised a hand and pointed at Shinichi's Nichirin Blade.
"Your sword carries... a very interesting aura."
Shinichi took a deep breath, raised his Nichirin Blade, and aimed its tip at Yoriichi. "Then allow me to demonstrate this swordsmanship for you!"
*VWOOM!*
"What?!"
*CLANG!*
*BOOM!!*
A vast expanse of the Infinity Castle was instantly sliced to smithereen!