Although the name of this Blood Demon Art was not mentioned in the original work, it had been used by Muzan Kibutsuji multiple times to turn the tide, nearly causing the entire protagonist group to fall.
However, this attack from Muzan Kibutsuji had already exposed the interior of the Infinity Castle, revealing the streets outside.
In a short time, this space had been destroyed by the indiscriminate attacks released by Muzan Kibutsuji.
Although the Infinity Castle did not pose much trouble for Roa, having none was better than having some.
Muzan Kibutsuji emerged from the shockwave, wielding the remaining whips, his exposed veins making him look like a malevolent demon. He moved towards Roa's position with an extremely strange posture, each whip darting towards Roa like arrows.
Now, it was time to sever the opponent's head.
"Breath of the Sun, Eleventh Form: Dragon Sun Halo Head Dance."
As he inhaled and exhaled, a scorching firelight surged in the distance. The crimson sword in Roa's hand glowed blood-red, a faint magical power enveloping the sword, flames wrapping around it, and a massive firelight shot up into the sky.
Muzan Kibutsuji sensed something was wrong and no longer held back; he had eight whips on his legs.
Muzan Kibutsuji had originally planned to wait until Roa got closer, as Roa's speed was incredibly fast. If the distance was too far, even Muzan Kibutsuji could not be 100% sure of hitting Roa.
But the situation had changed, and Muzan Kibutsuji could not afford to hesitate any longer; he had to strike first.
The eight whips on his legs were the fastest among all of Muzan's whips, each about seven meters long, moving faster than the nine whips on his upper body and his arm whips.
The ground cracked, and the atmosphere wailed as the whips shot out, creating sonic booms as they enveloped the area where Roa stood.
Muzan Kibutsuji's attack was swift, so much so that even the Hashira-level swordsmen of the Demon Slayer Corps, even when activating their marks and perceiving the world, could easily be killed by this move.
But unfortunately, standing here was Roa.
With the enhancement of the Transparent World and Sword Heart, even if Muzan Kibutsuji's speed was fast, it gradually slowed down in Roa's eyes.
His heartbeat quickened, adrenaline surged, and Roa's strikingly handsome face was fixed on Muzan Kibutsuji's position.
In the next moment, Roa moved.
Firelight streaked across the sky, and the magnificent flames erupted in an instant, transforming from a distant point into a massive fire dragon, rolling towards Muzan Kibutsuji's position.
As the heat waves rolled, the surrounding air temperature rose. The dragon head formed by the crimson sword collided with the whips Muzan Kibutsuji thrust out, easily severing them. The points of severance turned to charred remains.
The crimson sword shattered all the whips, revealing the fierce dragon head of the fire dragon. In an instant, all of Muzan Kibutsuji's extended whips were cut off, and Roa's figure vanished into the distance once more.
Like a meteor, like fleeting firelight,
Muzan Kibutsuji roared, his expression completely losing control; he could no longer remain calm.
The extreme heat radiating from the crimson sword and the burning sensation from the Breath of the Sun could not be ignored, even by the Demon King Muzan Kibutsuji.
The flames continued to explode, falling to the ground, and surprisingly did not extinguish immediately but kept burning.
The already chaotic space was completely shattered this time, the flames scorching the interior of the Infinity Castle. Even if the internal space of the Infinity Castle was destroyed, it would usually recover over time, but this fire was continuously suppressing the recovery speed of the Infinity Castle, even showing signs of spreading outward.
The scorching slashes turned into waves of heat, targeting Muzan Kibutsuji's position, repeatedly piercing and striking. The dragon head of the fire dragon lunged at Muzan Kibutsuji's body, the bone-searing heat constantly stabbing at his nerves. Muzan Kibutsuji extended his severed arms, transforming them into massive lumps of flesh, trying to resist Roa's strikes.
But when the flesh lump collided with the crimson sword, it melted away like snow under the sun. In just a breath, the massive, bloated flesh was completely burned away, and the momentum of the crimson sword remained unyielding, directly slashing towards Muzan Kibutsuji's head.
Muzan Kibutsuji attempted to retreat to avoid the strike, but under the enhancement of the Transparent World, every movement of Muzan Kibutsuji was completely under Roa's control. At such a close distance, how could he evade?
The crimson sword sliced into Muzan Kibutsuji's neck, the scorching sword pressing in relentlessly. Muzan Kibutsuji's eyes widened in fury, and the severed whips behind him regenerated, preparing to strike back at Roa.
But clearly, Muzan Kibutsuji's neck was not as hard as Roa's crimson sword. It merely slightly obstructed the strike before directly severing Muzan Kibutsuji's head.
With a tearing sound, Muzan Kibutsuji's head was cut off.
His head flew away but did not turn to ashes.
If the Demon King Muzan Kibutsuji could be easily eliminated, it would be laughable.
As the progenitor of demons, Muzan Kibutsuji had long surpassed the limits of demons. Even if his head was severed, he could not be completely destroyed.
After all, in the original work, both Akaza, who was Upper Moon Three, and Kokushibo, who was Upper Moon One, broke through the limits of demons when their heads were cut off, let alone Muzan Kibutsuji.
Only by completely destroying the opponent's heart and brain, and then severing Muzan Kibutsuji's head, could one truly kill him.
However, the pain from having his head severed still stimulated Muzan Kibutsuji at that moment.
"Ahhhhhhh!"
Even after his head was cut off, Muzan Kibutsuji continued to roar. His head transformed into a massive demon head in mid-air, the elegant and amiable demeanor of the past completely dissipating as it lunged fiercely at Roa.
Having lived for over a thousand years, as the progenitor of demons, Muzan's strength was unquestionable. Moreover, he possessed the ability to fully mimic; he could change the form of any part of his body.
This move from Muzan Kibutsuji was quite sudden. Who would have thought that even after severing his head, he could still transform into a demon head and lunge at them?
This move could be considered a hidden trick, but fortunately, Roa was not an ordinary person.
Reversing the crimson sword in his hand, Roa's cold voice echoed again.
"Breath of the Sun, Twelfth Form: Flame Dance Form of Sun Breathing."
The sword ignited with scorching flames, red flames wrapping around it as he slashed down in an arc approaching a perfect circle. Muzan Kibutsuji's fierce demon head took the full brunt of this strike, and it was not over yet. Roa gripped the crimson sword with both hands and delivered another strike, completely shattering Muzan Kibutsuji's head.
This was a double strike version of "Waltz," and its power was even stronger than the original technique.
The firelight enveloped the crimson sword as Roa's right arm exerted force, his muscles bulging, and the Dragon Blood within him boiled.
Muzan Kibutsuji's head turned to ash and dissipated. Even after being struck by Roa's crimson sword, Muzan Kibutsuji did not immediately perish.
Roa frowned. According to the principle of "smoke and no injury," the damage Muzan Kibutsuji sustained this time was not significant at all.
As the ash scattered, sure enough, Muzan Kibutsuji's head flew back to his bizarre body.
Roa did not sit idly by; this was not a turn-based game where they took turns striking. He gripped the crimson sword once more.
"Breath of the Sun, Seventh Form: Sunflower Thrust Form."
The crimson sword, entwined with swirling flames, thrust fiercely towards Muzan Kibutsuji's heart.
This thrust pierced through Muzan's body, the crimson sword emitting high temperatures that continuously burned the cells inside Muzan Kibutsuji.
Muzan Kibutsuji extended his arms, now charred and broken, and threw a punch at Roa. The whips behind him all aimed to ensnare Roa. Roa raised an eyebrow, knowing that Muzan Kibutsuji wanted to create distance to catch his breath, but Roa would not give him that opportunity.
Taking a step forward, this time he did not use the sword techniques of the Breath of the Sun but rather the techniques of the Sword God style.
Roa intended to test Muzan Kibutsuji again. If he continued to act this way, then sorry, what awaited him would be a thunderous strike.
Draw Sword Technique - Fire.
In fact, compared to the Draw Sword Technique - Thunder, the Draw Sword Technique - Fire was not particularly outstanding.
It did not possess the extreme speed of the Draw Sword Technique - Thunder, although it had slightly more power. However, this power could not compensate for the lack of speed.
Such techniques either required extreme speed or extreme power.
And the Draw Sword Technique - Fire had neither extreme speed nor the significant power to surpass the Draw Sword Technique - Thunder, so even though Roa could use it, he rarely employed it.
But now, compared to the Draw Sword Technique - Thunder, the true strength of the Draw Sword Technique - Fire lay in its burning properties against demons.
The Breath of the Sun specifically targets demons, and a swordsman proficient in the Breath of the Sun could emit a killing power equivalent to sunlight.
Although Muzan Kibutsuji could initially hold his own against Roa due to his immortality, once Roa switched his breathing technique, he could no longer withstand the burning sensation.
With Muzan Kibutsuji's regeneration ability, even if an ordinary swordsman's crimson sword struck him, he could immediately regenerate. However, against the progenitor of demons, the crimson sword capable of inflicting significant damage was somewhat lacking.
But now, Muzan Kibutsuji was facing Roa.
The temperature around Roa had already risen significantly. By the time Roa sheathed the crimson sword at his waist, Muzan Kibutsuji sensed something was amiss.
The places where his head and body had been severed by the crimson sword could not regenerate; the intense burning sensation continued to sear the wounds. Even Muzan Kibutsuji could not stop the spread of this power.
At this moment, Muzan Kibutsuji realized a terrifying problem.
The places where he had been severed by Roa seemed unable to regenerate.
The whips could still manage to suppress the burning sensation and regenerate from the severed parts, but this time, Muzan Kibutsuji's head could not.
Muzan Kibutsuji glared at Roa with a sinister gaze and said, "You little brat, I admit you are strong. How about this? You give me your blood. I don't know what secrets lie within you, but if you give me your blood, I will turn you into a demon. Don't be quick to refuse; becoming a demon grants you endless lifespan and an undying body, with the only cost being to consume some unknown humans."
The original cliff completely collapsed, and the so-called throne fell to the ground, with debris continuously raining down from above.
Roa looked at Muzan Kibutsuji expressionlessly, the crimson sword in his hand growing ever brighter.
Muzan Kibutsuji wanted to speak, but Roa allowed him to. Muzan Kibutsuji wanted to buy time to recover from his injuries, and Roa was also gathering his strength.
Roa's golden hair fluttered in the wind, and the Demon Slayer Corps uniform was no longer as neat as before. His left arm was exposed due to the upper half of his clothing being torn by Muzan Kibutsuji's shockwave, revealing Roa's slender arm, which was not particularly muscular. Roa's golden eyes fixed intently on Muzan Kibutsuji, a powerful aura emanating from him.
This aura made Muzan Kibutsuji feel quite uncomfortable. For over a thousand years, as the Demon King, he had been accustomed to having everyone bow before him. Yet now, he felt a sense of subservience towards Roa.
Muzan Kibutsuji's expression turned unnatural as he continued to speak to Roa, "So, what do you think? I can make you the second Demon King, a Demon King who does not have to obey my orders. How about it? Join me?"
At that moment, Roa smiled, his crimson-golden eyes revealing disdain. He replied coolly, "How pathetic to become a creature like you."
Muzan Kibutsuji was enraged by Roa's words. The whips embedded in the ground suddenly shot out, attacking Roa from all directions.
Roa replied expressionlessly, "Is that all you can do, Muzan Kibutsuji?"
The anger on Muzan Kibutsuji's face faded, and his eyes, now devoid of pupils, looked at Roa and said, "Do you think you can dodge a few moves? If you get hit by the next attack, you will die on the spot. The whips carry my blood, and they will act according to my will. The cells within them will not turn you into a demon but will destroy all your cells. Just one hit is enough to kill you. Don't let my attack hit you."
But in the next moment, Muzan Kibutsuji could no longer speak.
Flames surged as Roa gripped the crimson sword.
It was a blazing firelight. At that moment, when Roa moved, Muzan Kibutsuji recalled the fear he felt when facing Yoriichi Tsugikuni.
Fear surged like a tide, engulfing his entire being, the pain from injuries that had not healed even after three hundred years.
Roa drew the Nichirin Sword hanging at his waist, concentrating all his power into one point. The color of the crimson sword changed once more, becoming as dazzling as the sun. Even from a distance, Muzan Kibutsuji could feel the terrifying heat radiating from it.
If he were struck by this sword, even if he did not die, he would be severely burned.
He had to escape.
However, right now, if he could devour this guy, he would surely advance further. Even without the blue spider lily, he would no longer fear the sunlight.
Amidst his chaotic thoughts, Muzan Kibutsuji's expression turned resolute. He calculated in his heart that as long as he could withstand this move, he could use his Blood Demon Art to severely injure Roa again.
Such a powerful slash, executed by a human body, would undoubtedly be a tremendous burden.
As his thoughts turned, Muzan Kibutsuji made the most fatal mistake.
In reality, when Muzan Kibutsuji became distracted, his fate was already sealed.
If Muzan Kibutsuji had acted decisively and transformed into over seven hundred pieces upon sensing danger, he might have struggled a bit longer. But when Roa sensed his intentions, the remaining outcome was already clear.
This strike was incredibly swift, and Muzan Kibutsuji could not evade it. The high-temperature crimson sword directly split Muzan Kibutsuji's body in two, then shattered all the whips that came at him. In that instant of drawing the sword, the surrounding temperature rose once more.
The high temperature caused the air around to distort, and heat waves rolled.
The thoughts of Muzan Kibutsuji are still too naive.
By the time Muzan Kibutsuji realizes his mistake, he can only walk this irreversible path to the end.
The technique is ready to be unleashed again; sound waves begin to brew. At such a close distance, the opponent's sword has already struck him, and at this moment, Roa has no means of defense.
The scorching sensation splits his upper and lower body apart. The damage Muzan receives now is no less than what he suffered three hundred years ago. If he doesn't devour his opponent this time, even if he cultivates for another three hundred years, he may never return to his previous state.
Roa shows no mercy, neither dodging nor avoiding. The crimson sword, with its momentum unabated, strikes directly at Muzan's head. After already taking two blows, the head endures this strike, and Muzan's expression twists in agony as the crimson sword pierces through. It feels as if magma is being poured into his skull, and the terrible sensation goes without saying.
Meanwhile, the massive sound wave has also finished brewing.
As long as he releases it, even he will undoubtedly die.
But in the next moment, he senses that s is wrong.
A strong sense of crisis washes over him.
The opponent… has actually let go?
When the crimson sword pierced his skull, Roa decisively released it, and the burning crimson sword, like a shooting star, smashed Muzan's head toward the ground.
In that instant, Muzan's eyes narrowed. Suddenly, out of the corner of his eye, he saw another crimson sword at the opponent's waist.
The opponent had always carried two crimson swords; he had just subconsciously overlooked this one because it had not been used.
Realizing the danger, Muzan acted decisively. The sound wave he had been brewing was no longer released; the instinct to fear death outweighed his greed. His body began to disperse, preparing to escape as mere flesh.