The Ubuyashiki family, due to their blood relation, seemed to be cursed since Muzan became a demon a thousand years ago.
All the children born (especially males) were weak and sickly, and soon after birth, they would die. The Ubuyashiki clan followed the advice of the deity and married the daughters of the priestly clan for generations. Although this way allowed the continuation of their lineage, no one could successfully live to the age of thirty.
And this was the fate of Ubuyashiki and Muzan Kibutsuji.
Muzan Kibutsuji said expressionlessly, "Are you done? If you are, please leave."
Before he finished speaking, Roa's figure had already appeared in Kagaya Ubuyashiki's home. Roa raised his gaze to confront Muzan Kibutsuji, feeling the intense demonic aura emanating from him, along with that almost nauseating presence.
Roa frowned. Just this moment, with the transparent world opened, he could see Muzan Kibutsuji clearly.
The structure of his body was extremely bizarre, possessing five brains and seven hearts.
Roa didn't know how he had managed to stitch together five brains and seven hearts, but just this glance made Roa feel that he was quite tricky to deal with.
Muzan Kibutsuji's self-healing ability was definitely a level above that of Upper Moon One, Kokushibo.
In fact, even trying to kill him made Roa feel quite troublesome.
But it shouldn't be a big problem.
Thinking of this, Roa's hand reached to his waist, slowly grasping the Nichirin Sword, and coldly said to Muzan Kibutsuji, "The evil little demon of the Ubuyashiki family, I will personally take care of you today."
Drawing the sword from his waist, he rubbed the sheath with his fingers, instinctively using the Breath of the Sun.
The surrounding air began to heat up, and oxygen was inhaled into Roa's abdomen.
He began to visualize the moment he used the Sword of Light.
The passive activation of his sword heart allowed him to see every action and detail of the Sword of Light he released clearly.
So, should he change his breathing and give it a try?
The Sword of Light, akin to the Breath of the Sun, began to be attempted.
Swordsmanship refers to the techniques used to slay moving opponents.
Even if one were to strike directly from the front, it would only be easily evaded. Therefore, one must strike from below, horizontally, or even at an angle. A swordsman must put in the effort to unleash slashes in various ways to kill their opponent.
However, the Sword of Light was different.
It didn't require such techniques. It simply cut through everything with the fastest swing of the sword.
As long as one swung the sword, it was the ultimate speed, an unavoidable speed, devoid of any technique. Yet, precisely because it lacked any technique, it was the swordsmanship that required the most skill.
The frequency of his breathing began to change, and that scorching sensation began to spread. Then—Roa moved.
In that instant, his figure shifted.
His right foot stepped forward, his body's center of gravity lowered, and he sheathed the sword back into its scabbard at his waist, slowly gripping the katana at his side.
Clearly, there were no movements, yet an overwhelming sense of pressure had already appeared around Roa.
As long as Roa wished, the next moment would be a terrifying slash.
Only with extreme speed could he easily take the enemy's head.
Magic began to flow unconsciously, dragon blood began to boil, and the golden color in his eyes intensified.
With the transparent world opened, Roa concealed all his killing intent. This sword was terrifying, terrifying enough that if he wanted, he could easily take Muzan Kibutsuji's head in that instant.
But then what? What would happen?
Muzan Kibutsuji had already reached a point where even if his head was severed, he would not die. He had surpassed the limits of a demon; unless exposed to sunlight, he would not die at all.
To resolve this here would inevitably cause destruction around.
Suppressing the aura emanating from him, he shifted his breathing again, changing it to the Breath of Thunder. However, this move was no longer the Sword of Light but rather the Thunderclap.
Muzan Kibutsuji looked at Roa with a calm expression. He could sense the faint threat emanating from Roa, but it was cleverly concealed.
However, it was also true; how could someone who could kill Kokushibo be an ordinary person?
Muzan Kibutsuji then looked back at Kagaya Ubuyashiki, his expression cold as he said, "In that case, why not try to come to Infinity Castle? There, we can have a fair battle. What do you think?"
Roa revealed a mocking smile and said, "A 'fair' battle with you there? You really think highly of yourself, evil little demon of the Ubuyashiki family."
Muzan Kibutsuji's expression turned cold, looking at Roa with indifference, "If you keep talking nonsense, do you believe I will tear you apart on the spot?"
Roa remained unconcerned and said, "You can try."
Muzan Kibutsuji's hand suddenly moved, so fast it was almost unbelievable, directly reaching for Roa's chest.
Roa raised the Nichirin Sword in his hand and executed a Thunderclap, enveloping the sword in lightning, directly severing Muzan Kibutsuji's outstretched hand.
Muzan Kibutsuji looked deeply at Roa, and the severed right hand emitted a brief burnt smell at the point of fracture, but in the next moment, it quickly regenerated.
"Indeed, you are special. My instincts tell me that if I eat you now, I can achieve significant growth. But you, right now, won't let me eat you so easily, will you?"
Roa twitched the corner of his mouth. Who would let someone like you eat them?
Muzan Kibutsuji coldly said again, "This time, I will let you go. Come to Infinity Castle in a week. Our battle will unfold there. Whether you come or not is up to you, but you will only have this one chance. Let me see who will be the victor."
This statement was directed at Kagaya Ubuyashiki but was also meant for Roa.
After saying this, Muzan Kibutsuji expressionlessly looked at the wisteria flowers planted in the courtyard, revealing a look of disgust. In the next moment, his figure turned into an afterimage and vanished from the spot.
Roa did not attempt to intercept him; it was not the right time to stop Muzan Kibutsuji now. The area was filled with his own people, and a fight here would definitely cause trouble. Moreover, seeing Muzan Kibutsuji's confident attitude made Roa feel somewhat tricky.
Even if he could sever the opponent's head in an instant with the Sword of Light, and even if Muzan Kibutsuji transformed into seven hundred pieces to escape, Roa was confident he could cut through all seven hundred pieces in that moment.
But the problem was that this had to be done when the opponent was unprepared.
The current situation was that only the Nichirin Sword combined with the Breath of the Sun could inflict substantial damage on him. Just relying on the Sword of Light, even with incredible speed, might not necessarily kill him completely.
Thinking of this, Roa felt a bit of a headache.
Kagaya Ubuyashiki silently watched Muzan Kibutsuji's departing figure, deeply exhaling, and said to Roa, "This time, thanks to you, if it weren't for you, I might have died at his hands."
Roa didn't say much, simply accepting the gratitude straightforwardly. The situation was indeed as Kagaya Ubuyashiki said; without Roa, death would likely have awaited him.
Given Muzan Kibutsuji's character, he wouldn't care whether Kagaya Ubuyashiki was of his bloodline. Roa could also sense that Muzan Kibutsuji's combat power was definitely much s than it was three hundred years ago.
But it was understandable; with Yoriichi Tsugikuni's terrifying strength, it was likely that Muzan Kibutsuji had been left with a profound psychological shadow, so being prepared was reasonable.
Really, the situation was becoming increasingly troublesome.
Thinking of this, Roa stopped pretending and directly removed all the bandages tied around his head.
Kagaya Ubuyashiki looked at Roa in surprise as he took off the bandages and curiously asked, "Aren't you going to keep them on?"
Roa looked at Muzan Kibutsuji's departing figure and said, "He should have already seen my condition; I am not injured."
This was also the reason Muzan Kibutsuji did not act here.
Perhaps he had decided to completely eradicate the Demon Slayer Corps, no longer allowing them to take root and entangle with him generation after generation.
Roa walked outside and said, "Get a sword ready; there isn't much time left."
Roa did not go to sleep; he continued to sit in the chair, gazing at the night sky. The sky was so dark that not a glimmer of light could be seen, even the moon was obscured by dark clouds.
Was it the eternally long dark night, or the dawn that was about to arrive? Roa expressed that he was looking forward to it.
The long night stretched on, sitting in the chair and gazing at the night, his golden hair swayed slightly in the summer breeze. At that moment, Roa felt very poetic, like a hero about to vanquish a demon king, gazing at the moon on the eve of departure.
In an instant, his aura was elevated.
Just as Roa was immersed in his self-importance, outside, Tanjiro Kamadou, holding his Nichirin Sword, said to Roa, "Good evening, Brother Roa. By the way, why aren't you sleeping yet?"
This was Tanjiro Kamadou, who had just finished patrolling and was preparing to go home to sleep. Since he had training the next day, he would finish his tasks and then go home to sleep for three hours. This time was the happiest for Tanjiro Kamadou; the morning training often hit his confidence hard, and comparing himself to the Hashira made him realize his own level.
Although the other Hashira treated Tanjiro Kamadou well, the impact was still a bit too great.
There was still a gap. Currently, Tanjiro Kamadou had not unlocked his marks, nor had he experienced a battle with Akaza. The transparent world had not been developed, and he was left with only the Breath of the Sun, which he could not use for long due to excessive consumption.
In other words, Tanjiro Kamadou was really a bit useless right now.
Roa looked at Tanjiro Kamadou, who seemed to be deep in thought, and said, "Muzan Kibutsuji just came by."
Tanjiro Kamadou's expression changed instantly. His first reaction was to hurriedly look inside the house, but then he saw Roa's relaxed demeanor, and his expression gradually softened.
Tanjiro Kamadou covered his racing heart and said with a hint of dissatisfaction, "Brother Roa, don't scare me like that."
Roa shook his head, his face serious, and said, "This time, it's really going to be a showdown with him. The location is Infinity Castle, and the time is a week from now. I think you should just stay home and watch over Nezuko and the others."
Tanjiro Kamadou was slightly taken aback, but his expression became exceptionally serious as he said, "Brother Roa, I want to participate this time. I want to contribute. There's still a week left, and I will work hard."
Roa felt a headache coming on, thought for a moment, and said, "Well, that's fine. You should still be able to be of use."
Having the protagonist as a sidekick, destiny would surely be on his side. Hopefully, everything would go smoothly.
Seeing Tanjiro Kamadou looking tired, Roa didn't say much more and said to him, "Go inside and rest."
Tanjiro Kamadou knew that Roa usually sat in the courtyard, so he didn't say anything more and went inside, closing the door to the inner courtyard.
Roa closed his eyes for a moment, and when he opened them again, the sky was already dimly lit. In a daze, he seemed to see that figure again.
Roa stood up and walked outside.
The training of the Hashira began.
Of course, the Hashira wouldn't arrive so quickly.
The first to arrive would actually only be Mitsuri Kanroji.
The little girl has been clinging to Roa more and more recently, and every time they go on patrol, she gazes at him with longing eyes. At such moments, only a farewell kiss can soothe her.
Before Mitsuri Kanroji arrived, she took a bath, and as she approached, a faint fragrance emanated from her body.
The more Roa looked at Mitsuri Kanroji, the more he found her pleasing to the eye. Although she wasn't the type to leave a stunning first impression, her natural innocence was truly commendable.
Following the usual routine, Roa reached out and wrapped his arm around Mitsuri Kanroji's waist. The touch was soft, a feeling hard to describe, but it made Roa instinctively hold her tighter.
Compared to their first encounter, Mitsuri Kanroji seemed much calmer this time.
Though her cheeks were still flushed, she didn't pull away. Instead, she leaned closer to Roa.
From a distance, Tanjiro Kamado caught a glimpse of this scene and suddenly widened his eyes, his face turning red. As a young boy, he couldn't bear to watch and quickly turned his head away.
Roa gently held Mitsuri Kanroji's hand and said with a serious expression, "After this event is over, I'll take you to my hometown. What do you think?"
Mitsuri Kanroji nodded slightly, and Roa smiled, "Alright, then it's settled."
Since it was still early in the morning, it was impossible to act so boldly in broad daylight, so he decided to tone it down a bit.
However, toning it down didn't mean doing nothing.
Mitsuri Kanroji's hands weren't particularly delicate. On the contrary, they were a bit rough from recent sword practice.
This was a normal phenomenon for someone who practiced swordsmanship, as not everyone could be like Roa.
After lingering for a while, they finally waited for the first Pillar to arrive.
Naturally, it was Kyojuro Rengoku. Since Mitsuri Kanroji's home was relatively close, it wasn't surprising that he arrived first.
Roa greeted Kyojuro Rengoku, who responded with a loud and chee greeting, revealing a row of neat teeth.
As per the agreement, the remaining members of the Demon Slayer Corps arrived one after another.
Roa didn't waste any time and quickly started the training session, using the Transparent World to point out flaws in their movements.
These might not seem like much to Roa, but for the Pillars, they were incredibly valuable.
Perhaps in Roa's eyes, these were just casual actions, and the improvements in strength weren't significant, but that was relative to the Mark and the Transparent World.
Both epiphanies happened in an instant, and the abilities they could enhance were considerable. However, one consumed one's life force to convert into power, while the other required innate talent.
Compared to the Pillars' self-practice, Roa's guidance led to almost visible improvements in strength.
He had each Pillar spar with one another to identify their weaknesses and areas for improvement. Sometimes, Roa would step in to guide them, and his method was simple—he would thoroughly defeat them in every aspect.
Among the Pillars, the strongest performer was the Stone Pillar, Gyomei Himejima.
Roa realized that Gyomei Himejima's strength was enough to go head-to-head with Upper Moon Three.
Gyomei Himejima's weapon was also quite peculiar—a broad axe and a flail connected by a long chain. The weapon contained a high purity of "Scarlet Crimson Iron Sand," and despite its weight, Gyomei could wield it effortlessly.
Given Gyomei Himejima's physique, Roa could understand how he could wield such a heavy weapon with ease. Although his strength might be slightly inferior to Mitsuri Kanroji's, combat prowess wasn't solely determined by strength.
Roa thought that if Mitsuri Kanroji were to face Gyomei Himejima, she would likely lose with a few dozen moves due to the difference in skill.
At this thought, Roa's gaze once again fell on Mitsuri Kanroji, who was currently sparring with Kyojuro Rengoku. It was worth noting that Mitsuri Kanroji had also obtained her unique Nichirin Sword, which, like in the original story, was a flexible, whip-like sword with strong resilience. The sword had a chaotic pattern, and the scabbard was white with a gray-green hilt adorned with a heart-shaped, pink tsuba resembling a four-leaf clover. The sword itself was pink and could be folded into the scabbard.
Although the sword's design was quite unusual, it was certain that Mitsuri Kanroji's attack speed wasn't slow, and even Kyojuro Rengoku had to be cautious of her strikes.
Roa observed for a while and then shook his head—there was still much room for improvement.
After dealing with Gyomei Himejima and then the self-proclaimed flamboyant Sound Pillar, the morning training session came to an end.
However, at the end, Roa didn't rush to dismiss everyone. Instead, he gathered them and said, "One week from now, in the Infinity Castle, we will face Muzan Kibutsuji in the final battle. I hope everyone is prepared and doesn't get injured. Get ready for the upcoming challenge!"