The bluish-green blade glow pierced through the darkness like the first light of dawn—bright yet not blinding, instantly illuminating the entire battlefield.
Shinichi didn't employ any complex sword forms, merely executing a simple horizontal slash.
Yet the Breath of Life energy contained within that blade glow was exceptionally dense, pure, and warm, carrying his most sincere respect for the Demon Slayer Corps seniors.
Sss—
An extremely faint cutting sound echoed as a thin, bluish-green glowing line appeared on the neck of the demonized Jigoro
There was no pain, no struggle.
The short figure remained standing in place.
The crimson red belonging to demons rapidly faded from his turbid eyes, replaced by long-lost human clarity and gentleness.
Looking at Zenitsu who was weeping uncontrollably nearby, Jigoro's face, now free from ferocity, slowly revealed a benevolent smile.
"Zenitsu... my good child." His voice was no longer hoarse and broken, having regained the warmth and firmness from when he was alive.
"Don't let this old man down."
Hearing his master's words, Zenitsu nodded desperately, tears blurring his vision, choked too emotional to speak a single word.
He could only nod repeatedly, as if trying to engrave every word and expression of his master deep into his soul.
Jigoro smiled contentedly.
He raised his head, his gaze extending beyond Zenitsu into the distance.
Visions seemed to appear before his eyes—scenes from his life: living, fighting, teaching disciples.
Those images represented his life as a human, as a Demon Slayer Corps swordsman, as a cultivator—the proudest achievements of his lifetime.
Then, Jigoro's body began to disintegrate.
Not with the pain and distortion of evil demons turning to ashes, but with a peaceful, gradual dissipation like fallen leaves returning to their roots.
Golden light particles slowly drifted from his body, accompanied by the bluish-green glow, dispersing like fireflies on a summer night.
Finally, when those light particles completely merged with the air, Jigorō Sakonji's body completely vanished.
Only residual glimmers flickered briefly within Zenitsu's tears before fading into nothingness.
"Master... Master!!!" Zenitsu finally cried out loud, kneeling on the ground. "I won't... I will absolutely not let you down!!!"
Tanjiro and Inosuke stood silently behind him, not interrupting.
All they could do was protect this companion who had just lost his dearest loved one in their own way.
Shinichi sheathed his sword, sighed softly while looking at Zenitsu's back, then stepped forward and crouched beside him.
Placing his hand gently on Zenitsu's shoulder, the power of life slowly flowed into Zenitsu's body, healing some of his injuries.
"Zenitsu." Shinichi's voice was calm yet powerful. "Remember your words. You must live well, live to become the person your master would be proud of. The legacy of the Thunder Pillar may now rest upon you from this day forward."
Zenitsu raised his head, face streaked with tears, yet his eyes shone with unwavering determination.
He nodded firmly, wiped his face roughly with his sleeve, stood up, and tightly gripped his Nichirin Blade.
"Shinichi-senpai, I understand!" His voice still trembled slightly but had regained its strength. "I won't let my master down! Even if I only know Thunder Breathing First Form... I... I will use this single form to slay all the evil demons in this world!"
Shinichi gave a slight nod, his gaze shifting to Kaigaku, who lay in a pool of blood not far away.
At this moment, Kaigaku was clutching the deep, bone-exposing wound on his chest, struggling to get up.
The strike delivered by the demonized Jigoro before his death had nearly split his chest open, and blood continued to gush from between his fingers.
However, as a swordsman who had trained in Thunder Breathing, his vitality was tenacious, and he was not yet dead.
Seeing Shinichi's gaze sweep over him, Kaigaku's face turned deathly pale, his eyes filled with fear.
He opened his mouth, perhaps to beg for mercy or to make excuses.
But Shinichi gave him no chance.
"Your master gave you that final strike—it was his last 'lesson' to you as a teacher," Shinichi said calmly.
"As for the path you take afterward... it has nothing to do with me."
He turned away, not sparing Kaigaku another glance.
Kaigaku was stunned, then a flicker of wild joy flashed in his eyes.
The Forest Pillar hadn't killed him? He was letting him go?! This was too good!
As long as he survived, as long as he lived, there would still be a chance!
Overwhelmed by this sudden relief, Kaigaku disregarded everything else.
Even as blood poured from his chest, he struggled to his feet and staggered into the depths of the darkness, fleeing for his life.
"Shinichi-senpai! Why did you let him go?!" Tanjirou shouted in confusion. "Someone like him..."
"He won't make it out of the Infinity Castle alive," Shinichi said, looking at Tanjirou with a calm tone.
"His wounds, his fear, his cowardice... are more fatal than any demon. And..."
Shinichi glanced slightly to the side, looking at Zenitsu.
Zenitsu tightened his grip on his sword, gazing in the direction where Kaigaku had disappeared.
There was no hatred in his eyes, only a complex sorrow.
He said quietly, "That was the final punishment Master left for him... Thunder Breathing has already destroyed his internal organs."
Tanjirou fell silent and Inosuke snorted but said nothing more.
But just then...
A Kasugai crow suddenly swooped down from above, landing on Shinichi's shoulder and urgently cawing.
"The Sound Pillar is in critical danger! The Master is in critical danger! The Forest Pillar is requested to provide immediate support! Immediate support!"
Shinichi frowned, then turned to Tanjirou and the other two. "Can you still fight?"
"Yes!" Tanjirou answered without hesitation.
"I haven't had enough yet!" Inosuke waved his dual swords.
Zenitsu took a deep breath and tightened his grip on his Nichirin Blade. "I can do it."
"Good." Without another word, Shinichi transformed into a bluish-green streak of light, speeding toward the direction indicated by the crow, with Tanjirou and the other two close behind.
...
Elsewhere in the Infinity Castle, near the core area.
Gruesome—that was the most fitting description for the scene before them.
Uzui Tengen was drenched in blood, his Demon Slayer Corps uniform torn in multiple places, revealing numerous bleeding wounds.
Yet, the dual swords in his hands still danced like the wind, the chained Nichirin Blades cutting deadly arcs through the air, slicing wave after wave of low-level demons into pieces.
Although they were all low-level demons, there were far too many of them!
They surged from all directions, crawling out from the ceiling, the walls, and the cracks in the ground, endless and seemingly impossible to exterminate.
These demons, though not particularly strong, were terrifying in number and fearless in their attacks.
As soon as one wave was cut down, the next would quickly rush in.
"Damn it! How long are these unrefined scum going to keep coming!" Uzui Tengen gasped for breath, slicing three charging demons in half with a single blade stroke, only to have five more immediately rush from the side!
Not far behind him, over a dozen swordsmen of various ranks were desperately fending off the demons that had slipped through.
Though their combat abilities fell short of the Hashira level, their coordination—honed through Hashira training—made them remarkably effective.
Yet even the most skilled swordsmen grow weary, and after relentless battles, several Demon Slayer Corps members had already made the ultimate sacrifice.
Further behind Uzui Tengen and the Demon Slayer Corps members lay a narrow, concealed chamber.
Inside this sanctuary, the three Ubuyashiki siblings were protected in the innermost circle.
The young leader, eyes shut tight with furrowed brows, beaded sweat glistening on his forehead.
His mind operated at an unprecedented pace, processing endless streams of intelligence from Kasugai crows across all battlefronts.
Combined with Yushiro's Blood Demon Art, Kiriya was mapping the structure of the Infinity Castle in his mind, rapidly piecing together and calculating the entire battle's progression.
"Yushiro-san, intense demon energy detected in the third-level sector upper left. Please confirm if this is Kokushibo's coordinates."
"Understood. Send me another Kasugai crow!" Yushiro responded, eyes still closed.
At that moment, a Kasugai crow swooped into the chamber, alighting on Kiriya's shoulder with urgent caws.
"Shinichi-san has resolved the conflict in his area and is en route to provide support. Excellent."