Riezel was completely speechless.
He had indeed seen Yoriichi as a level-up opportunity, but he had never expected that Yoriichi would become such a formidable opponent worth challenging in this way.
He knew that Yoriichi was not only strong but also had limitless potential.
What others had to risk everything to awaken, Yoriichi was born with.
What others might spend their whole lives searching for and might never achieve, Yoriichi had achieved them naturally since childhood.
Not only was Yoriichi the founder of the breathing style and the only person in this world who could defeat Muzan with sheer strength, but the breathing style he founded also became the source of power humanity used to fight demons.
In many ways, Yoriichi seemed more like the main character of this world than Tanjirou.
Yoriichi even managed to instantly grasp the thirteenth sword form of Sun Breathing upon encountering Muzan to defeat him.
Riezel's potential was already at a level that would astonish a goddess like Loki and even the many gods in Orario. Given this, Yoriichi might actually not fall too short when compared to Riezel.
Even so, Riezel still couldn't imagine that Yoriichi, even after death, would discover further potential within himself by succeeding in evolving Sun Breathing like he did.
Regardless, Riezel's success was not only due to his innate potential but also because he had another world's breathing techniques as a reference, which validated and confirmed the breathing techniques of this world, eventually leading to his success.
However, what about Yoriichi?
Yoriichi clearly had no reference and simply observed the entire process of Riezel evolving Sun Breathing, yet he smoothly completed this dangerous endeavor that had troubled Riezel for three months easily.
From this, it was clear why Yoriichi was seen as a god in Kokushibou's eyes and a monster in Muzan's.
*Ba-dump!*
Suddenly, Riezel heard a strong heartbeat.
*Ba-dump!*
Upon hearing it again, Riezel realized the source of the heartbeat was actually him.
At this moment, his heartbeat began to quicken, his blood boiled, and a surge of high-spirited emotions rose within him.
Such an emotion, as if boundless heat was surging through his chest, was very familiar to him.
It was the feeling of having adrenaline activated when encountering obstacles, strong enemies, challenges, and difficulties.
Truthfully, he had long missed this feeling.
After about half a year, he finally felt it again.
"Huu..."
Riezel took a deep breath, letting a large amount of air flow into his lungs before assuming an offensive stance.
Seeing this, Yoriichi's eyes narrowed, and he also took up an offensive stance.
"Huu..."
Yoriichi also inhaled a large amount of air, fully stimulating his body.
Gradually, the high temperature began to seep from both swordsmen who mastered Sun Breathing, causing the air around them to slightly distort.
"I'm coming." Riezel said briefly.
"Bring it on." Yoriichi nodded.
Saying these, their gazes collided in the air, sparking intense friction.
In the next moment—
""Sun Breathing - First Form…""
*Whoosh!*
Two figures charged forward simultaneously, vanishing from their original spots.
""Dance!""
As two blazing flames appeared out of nowhere, Riezel and Yoriichi appeared in front of each other, both unleashed a slash that gathered all their strength.
*DING—!!!*
As they clash, a deafening clash erupted, causing the sun's flames to burst from the two swordsmen, creating a searing shockwave that spread in all directions like a fiery explosion.
Two Nichirin Swords, wrapped in flames, collided at the center of the blast—one sword unleashed fiery bursts, while the other engaged in fierce friction.
In an instant, the two swordsmen were locked in intense combat, their flaming swords began clashing at breakneck speed.
*Clang!* *Cling!* *Clang!* *Cling!*
*Clang!* *Cling!* *Clang!* *Cling!*
Riezel and Yoriichi each released scorching slashes toward each other, their fiery swords constantly flaring and crashing.
Riezel reached an unprecedented level of focus as if he had abandoned all defense, letting his intense emotions guide him. He slashed from every angle at Yoriichi, making the flames blaze fiercely with each strike.
Despite Riezel's intense assault, Yoriichi remained entirely on the offensive. His eyes, clear as glass, saw through everything, and he responded with countless fiery slashes.
As their searing slashes continued to appear and collide, some soaring into the air and others shooting in all directions, they released intense heat into the surroundings, leaving red-hot trails on the ground as if molten lava had passed through.
*BOOOM!*
Before long, an explosion raged like a storm, ravaging the mountaintop and raising clouds of dust and debris, resembling a natural disaster.
*DING—!!!*
At one point, a loud clash rang out again.
From within the fiery explosion, a figure was sent flying back, skidding across the ground.
Surprisingly, it was Riezel who was being pushed back and was on the losing end.
*Whoosh!*
With a sound like space being torn apart, Yoriichi emerged from the explosion and twisted his sword, causing countless fiery slashes to surge forth and relentlessly strike Riezel.
Still skidding backward, Riezel raised his sword to block, fending off the incoming fiery slashes, which caused flames to flicker around him.
Yoriichi, however, clearly showed no mercy.
Not only did his attack remain fierce, but even as Riezel blocked his storm of slashes, he continued to swing his sword tirelessly, breathing steadily and moving like a perpetual motion machine, endlessly slashing.
'Dance', 'Clear Blue Sky', 'Raging Sun', 'Fake Rainbow', 'Fire Wheel', 'Burning Bones, Summer Sun', 'Sunflower Thrust', 'Solar Heat Haze', 'Setting Sun Transformation', 'Beneficent Radiance', 'Sun Halo Dragon Head Dance', 'Flame Dance'—Yoriichi cycled through all sword forms of Sun Breathing in sequence, creating a relentless cycle of slashes that attacked Riezel with utmost ferocity.
Clearly, this was the thirteenth form of Sun Breathing—an unending sequence of sword form that formed a perpetual cycle, drawing the enemy into a sun-like orbit, enduring a ceaseless and searing onslaught.
Yoriichi completely unleashed his strength, starting with the sword form he had used to deal with Muzan before his death, dragging Riezel into the hell of the sun's flame.
With Yoriichi's current strength, such an all-out assault, constantly using Sun Breathing's sword forms without pause, was quite terrifying.
As a result, Riezel was driven back in the storm of blazing slashes and had to retreat from Yoriichi's offensive.
However, Yoriichi clearly had no intention of letting Riezel get away. He quickly transformed into a bright sun, chasing Riezel and enveloping him in the wheel of fire.
Under this circumstance, even Riezel was subtly struggling to keep up.
*Clang!*
In the end, with a crisp sound, Riezel's sword was deflected.
*BOOM!*
In an instant, Yoriichi's blazing slash landed immediately, causing a massive explosion on the ground that sent Riezel flying.
Riezel was thrown through the air, crashing into a rock before twisting his body mid-air, stabbing Hermit into the ground to stabilize himself.
Even so, Riezel and his sword were violently thrown nearly a hundred meters, leaving a gaping trench on the ground, a shocking sight.
"Sun Halo Dragon Head Dance!"
Not stopping, Yoriichi transformed into a fire dragon, soaring and swooping toward Riezel.
Inside the fire dragon, Yoriichi's high-speed slashes cut through the air and explosive flames, targeting Riezel's shoulder, side, thigh, and ribs.
*Pssst!* *Pssst!* *Pssst!*
Yoriichi's blazing slashes sliced through Riezel's body, leaving his shoulder, side, thigh, and ribs severely torn. Yet, despite such damage, not a single drop of blood spilled from him; he merely swayed like an illusion and slowly vanished.
"Fake Rainbow!"
Riezel transformed once again into the sun's flame, appearing behind Yoriichi in a flicker.
"Setting Sun Transformation!"
Yoriichi, as if foreseeing the future, instantly leaped into the air, evading the slash Riezel had aimed from behind. Following this, in an inverted stance, Yoriichi swung his sword, wrapped in blazing flames, horizontally toward Riezel's neck.
"Burning Bones, Summer Sun!"
Faced with the intense strike coming at him, Riezel twisted his sword, rapidly swinging it to unleash a vortex of flames that not only deflected Yoriichi's scorching slash but also sent flames swirling toward him.
"Fire Wheel!"
Yoriichi performed a somersault and, undeterred by his failed attack, slashed again in mid-air, sending a fire-wrapped, arc-shaped vertical slash toward Riezel.
*BOOM!*
Soon, the flaming slash and the vortex of flames collided, exploding with a roar, causing the flames to surge wildly.
"Clear Blue Sky!"
Yoriichi, not yet having descended from the air, linked seamlessly into the next sword form. He swung his sword around him, tracing a circle like the sun's outline, pulling the turbulent flames into a fiery orbit that slashed toward Riezel.
"Raging Sun!"
Riezel immediately countered with an infinity-shaped slash, transforming his flames into sharp, symmetrical fire blades that sliced through the incoming flames.
In the blink of an eye, Riezel and Yoriichi exchanged countless blows, employing various Sun Breathing's sword forms against each other relentlessly.
The exchange of attacks and defenses was not only incredibly tight and coherent but also intensely fierce.
It couldn't be helped.
A moment's slip could mean one side's complete annihilation, consumed entirely by the blazing sun's flames.
"Beneficent Radiance!"
Yoriichi, still airborne, took advantage of his higher position and unleashed a spiraling slash from above at Riezel that spread out like a storm.
"Sunflower Thrust!"
Riezel quickly raised his sword, making a ring of flames surge around it before launching a rapid thrust toward the airborne Yoriichi.
*BOOOM!*
It was unknown how many times the sounds of swords clashing and explosions echoed on the mountaintop.
Reddish flames burned brightly on the mountaintop, reflecting the sun in the sky and continuing to blaze, showing no signs of extinguishing.