The Sun’s Relentless Blaze

The battlefield was a chaotic tableau of blood, sweat, and ash. Muzan stood at the center of it all, a grotesque and towering figure, his monstrous form pulsating with malice. Surrounding him, the broken forms of Tanjiro's closest friends lay scattered. Inosuke, Zenitsu, Kanao, and even the Hashira—all were either unconscious or barely able to move, each a testament to their desperate struggle against the King of Demons.

Tanjiro knelt among them, his chest heaving as he clutched his sword tightly. His body trembled—not from fear but from the sheer weight of the moment. His friends, his family, his world—all depended on him now. He closed his eyes, recalling Bell's calm, measured voice during their training.

"What you need isn't just strength. It's control. Master the chaos, and you'll master yourself."

As Tanjiro opened his eyes, a profound calm washed over him. His Demon Slayer Mark flared to life, glowing with renewed vigor. The world before him shifted, the haze of battle giving way to perfect clarity. He could see Muzan's body in intricate detail—every muscle contraction, every twitch of his grotesque appendages. It was the Transparent World, a skill that had once eluded him but now came naturally.

The final piece fell into place as Tanjiro exhaled slowly. His body moved on instinct, entering the Selfless State, a realm of absolute focus and tranquility. Muzan's murderous aura no longer phased him; it was as if the entire battlefield had stilled, leaving only him and his enemy.

"Sun Breathing..." Tanjiro muttered, his voice steady. He adjusted his grip on his blade and whispered a silent prayer to his family, to his father, and to the legacy of the Breath of the Sun.

In that instant, he found the answer—the elusive Thirteenth Form of Sun Breathing.

The Thirteenth Form wasn't a single strike or maneuver but a relentless, flowing combination of all twelve forms of Sun Breathing executed in seamless succession. The idea was simple but terrifying in its execution: the user would keep attacking, cycling through each form without pause, creating a continuous assault designed to overwhelm even the most resilient of foes.

Tanjiro charged forward, his blade igniting like the dawn breaking through the darkness. His movements were faster, sharper, and more precise than ever before.

"First Form: Dance!" His blade struck Muzan's chest, the force creating a burst of fiery sparks.

"Second Form: Clear Blue Sky!" He spun, his sword cleaving through Muzan's outstretched tendrils.

"Third Form: Raging Sun!"

"Fourth Form: Burning Bones, Summer Sun!"

Each form flowed seamlessly into the next, a symphony of fire and steel that left Muzan on the defensive. For the first time, the Demon King found himself retreating, his regeneration struggling to keep pace with the damage Tanjiro inflicted.

But Muzan was not so easily defeated. He roared, his monstrous form writhing as he unleashed a barrage of attacks. Tentacles lashed out, claws raked through the air, and his Blood Demon Art filled the battlefield with a deadly shockwave.

Tanjiro pushed through, his body screaming in protest. His blade became an extension of his will, slicing through Muzan's onslaught with unyielding determination.

Yet, as the minutes stretched on, it became clear that even Tanjiro's newfound strength had its limits. His breaths grew labored, his movements slowing ever so slightly. The Thirteenth Form, for all its power, demanded a level of endurance that no human could sustain indefinitely.

Muzan seized the opportunity, his tendrils crashing into Tanjiro and sending him sprawling. The young slayer coughed, blood splattering the ground as he struggled to rise.

A slow clap echoed through the battlefield, cutting through the tension like a blade. All eyes turned to Bell, who stood calmly at the edge of the fray, his crimson eyes gleaming with amusement.

"Well done, kid," Bell said, his voice carrying an edge of pride. "You've exceeded my expectations."

Muzan snarled, his grotesque form twisting as he turned to face Bell. "And who are you to speak to me in such a tone, human?"

Bell stepped forward, his posture relaxed but radiating an aura of absolute confidence. "I'm the one who's about to put you in your place," he said, his tone dripping with disdain. "All that bluster, all that power, and yet you're struggling against a child. Pathetic."

Muzan's eyes flared with rage. "You dare mock me? I am perfection! I am eternity!"

Bell chuckled, shaking his head. "If this is perfection, then I'm disappointed." He glanced at Tanjiro, who was still catching his breath. "Watch closely, kid. You're about to see what true mastery looks like."

Bell drew his blade with deliberate slowness, the motion alone exuding a sense of inevitability. The air around him seemed to ignite as his blade caught the light, glowing with an intense, fiery brilliance.

"Sun Breathing," Bell said, his voice calm and measured. "Let me remind you, Muzan, what real fear feels like."

He moved, and in an instant, Muzan's arm was severed, the limb disintegrating into ash before it even hit the ground. Bell's speed was incomprehensible, his strikes precise and devastating.

"First Form: Dance," Bell said, his blade carving through Muzan's tendrils with surgical precision.

"Second Form: Clear Blue Sky," he continued, his movements flowing effortlessly into the next form.

Unlike Tanjiro, who had to fight with every ounce of his being to sustain the Thirteenth Form, Bell executed it as if it were second nature. His mastery of Sun Breathing was absolute, each strike landing with unerring accuracy.

Muzan roared in frustration, his form contorting further as he unleashed the full extent of his power. The ground cracked beneath him, and his tendrils lashed out in every direction, creating a whirlwind of destruction.

But Bell was unfazed. He weaved through Muzan's attacks with ease, his movements impossibly fluid.

"Is this all you've got?" Bell taunted, a smirk playing on his lips. "You're not even worth my time."

Muzan's fury reached its peak, and he abandoned all pretense of defense. His tendrils converged on Bell, each strike aiming to obliterate him.

But Bell didn't flinch. With a single, fluid motion, he severed Muzan's tendrils, leaving the Demon King momentarily stunned.

"You're starting to bore me," Bell said, his voice cold. "If you're going to flee, do it now. Otherwise, I'll end this."

Muzan hesitated—a flicker of doubt crossing his monstrous features. For the first time, the King of Demons was genuinely afraid.

Realizing that he couldn't overpower Bell, Muzan made his move. His form began to shift, tendrils retracting as he prepared to retreat into the shadows.

But Bell was faster. With a single step, he closed the distance, his blade slicing through Muzan's escape route. The Demon King howled in frustration as he was forced to stay and fight.

"You're not going anywhere," Bell said, his voice like steel. "Not until I'm done with you."

As the battle raged on, Tanjiro watched in awe, his body still trembling from exertion. Bell's mastery of Sun Breathing was unlike anything he had ever seen, a perfect blend of power, precision, and control.

But even as Bell dominated the battlefield, Tanjiro couldn't shake the feeling that this was far from over. Muzan was cornered, but he was still the King of Demons—a creature of pure malice and survival.

The dawn was still hours away, and the final confrontation had only just begun.