Even if that wasn't the case, Kamado Tanjiro was the only one who could access Sun Breathing, essentially the protagonist's panel.
But how should he find this young man?
There were so many mountains in this area. Searching one by one would be too troublesome.
Suddenly, Roa's eyes lit up. He remembered that when Tanjiro fought against his demonized sister Nezuko, the Water Hashira had intervened.
So, if he wandered around the areas under the Water Hashira's jurisdiction, he would likely encounter Kamado Tanjiro.
This successfully narrowed down the target range.
By the afternoon, a black-feathered crow landed on Roa's shoulder, cawing, "The Master calls you, the Master calls you."
Roa raised an eyebrow and extended his hand. The crow hopped onto his palm and continued, "Go to the Demon Slayer Corps headquarters to receive your Nichirin Sword! Go to the Demon Slayer Corps headquarters to receive your Nichirin Sword!"
Roa nodded. The Demon Slayer Corps headquarters was actually on the mountaintop above.
He had been there before, but the location wasn't where the Master resided; it was a bit more secluded.
That place was where the Demon Slayer Corps issued weapons. Roa had been there before, having received his uniform there last time, so he was quite familiar with the place.
After walking up the mountain for a bit, he easily found the courtyard with the clear landmark. After walking forward a few steps, he saw a Demon Slayer Corps member wearing a mask, his face obscured, with two companions beside him.
Upon seeing Roa, the man nodded slightly, and the crow that had been following Roa flew down from his shoulder, cawing twice, saying, "Roa! Roa!"
The Demon Slayer Corps member pointed to a rather ancient-looking Nichirin Sword on the table, coughed lightly, and said to Roa, "Take a look. How is this weapon?"
Roa nodded, took the Nichirin Sword in his hand, unsheathed it, glanced at it, and flicked it with his fingers.
The sword was a typical katana, long and narrow with a curved tip.
The material of the Nichirin Sword wasn't particularly special. Its only unique feature was its ability to fuse with breathing techniques to unleash extraordinary power.
After swinging it a few times, Roa raised an eyebrow. This Nichirin Sword didn't feel quite right in his hands.
For a Sword King like Roa, unless a weapon was exceptionally good, the rest were more or less the same.
In the hands of a Sword King, even medium and low-quality weapons could unleash unimaginable power.
Roa was currently in such a situation. In the world of "Mushoku Tensei," he could rely on magic swords, but this world prohibited magic, so he couldn't bring his magic sword over. This created a somewhat awkward situation.
However, it should still be effective against demons. The sword emitted an aura opposite to that of demons—a subtle feeling, likely the rules of this world and the constraints on demons.
Now that he had the sword, it was time to start his hunting mission.
With that in mind, Roa smiled at the man and was about to leave when the man suddenly called out to him, his face showing respect as he said, "The Master told me that at the next Hashira Meeting, he will announce your appointment as the Thunder Hashira."
Roa was slightly taken aback and scratched his head, asking, "He alread knows?"
What Roa meant was that the Master already knew about his escape from Upper Moon Four.
Perhaps for Roa, this might be a bit humiliating, but for the Demon Slayer Corps, being able to face an Upper Moon and retreat calmly was proof of immense strength.
The Demon Slayer Corps member nodded and said in an admiring tone, "From now on, we should address you as Lord Thunder Hashira."
Roa waved his hand and said with a wry smile, "We're all family here. No need for formal titles like 'Thunder Hashira.' Alright, I'll take my leave now. You continue with your duties."
With that, Roa walked away.
The Demon Slayer Corps member watched Roa's retreating figure and muttered to himself, "Such a young age and already achieving so much. The recent Hashiras are truly a bunch of monsters."
——
After obtaining his new weapon, Roa inquired around and managed to learn the general area under the Water Hashira, Tomioka Giyuu's jurisdiction. However, this area was quite far from the headquarters and covered a large map, mostly consisting of small mountain villages.
Such villages, needless to say, were natural havens for demons. The population was sparse, and people lived scattered. Even if one or two went missing, no one would notice.
After all, in towns with larger populations, although there were plenty of "small snacks," causing a commotion would be troublesome for demons.
This meant that demons in the mountains could act with impunity.
Roa, relying on his residual memories, took out a map and studied it repeatedly, marking possible locations where Tanjiro might appear with small circles.
Roa planned to search each one.
One of the tasks mentioned that the more he participated in the plot and the more he altered the world, the more temporal power he would gain.
If he directly saved Tanjiro's family, the plotline would completely change. Would that count as altering the plot?
By nightfall, Roa began his patrol, targeting the nearest mountain to start his night watchman duties.
Carrying his sword and a lantern, he walked up the rugged mountain path.
To Roa's surprise, the area under the Water Hashira's jurisdiction was much more peaceful. After walking for a while, he didn't sense a single demon.
Roa frowned. He had come up the mountain partly to test the power of his new Nichirin Sword by slaying a few demons.
With that in mind, Roa quickened his pace, quickly scouting the area. Finding no traces, he prepared to descend and search another mountain.
This time, he chose a more remote mountain area. According to Roa's estimation, there should be at least two or three demons hiding there.
Roa continued to stride confidently up the mountain, carrying his oil lamp.
In the pitch-black and silent night, the flame of the lamp stood out strikingly. The wind gently brushed against the glass cover of the lamp, inside which the candle burned brightly.
The rugged mountain path was difficult to navigate, especially at night. The intermittent chirping of insects added to the eerie atmosphere.
Springtime on the mountain always brought a variety of insects, which became particularly active at night.
This time, his efforts were not in vain. Although he still hadn't found the Kamado family, he managed to successfully capture a lone demon.
It was a female demon, with a typical delicate appearance, but traces of blood remained around her mouth, and her fangs were visible when she opened it.
Without wasting any words, Roa immediately drew his Nichirin Sword and engaged in combat.
First, he severed the demon's arm. Roa didn't use any breathing techniques, and after the arm was cut off, the demon's recovery speed slowed significantly, though it still continued to heal at a sluggish pace.
This time, Roa didn't hold back. With a flash of his sword, he unleashed the Thunder Breathing technique combined with the Nichirin Sword, and the injuries inflicted on the demon became irreparable.
The female demon howled in pain, her cries echoing through the silent mountain forest.
"Damn demon slayer, you bastard."
Before she could finish her sentence, Roa swiftly decapitated her. The head flew high into the air, and this time, it didn't move again after being severed by the Nichirin Sword.
Her face contorted in agony, and burn-like marks appeared on her neck before her head turned to ash.
Roa raised an eyebrow. The moment the Nichirin Sword struck, he had been fully focused on observing the changes in the demon. As he had expected, something had indeed changed within her. The simplest explanation was that the concept of her regeneration had been completely shattered.
"So this is the power of the Nichirin Sword? Truly, each tool has its specialty," Roa murmured to himself.
If it had been the old Roa, unless he used magic to completely obliterate the demon, she would have still been able to revive. But with the Nichirin Sword, as long as the attack was powerful enough, the demon couldn't recover.
Having discovered the demon, Roa became more meticulous in his search of the mountain.
He found a second demon further down the mountainside. This time, it wasn't a female demon but a scar-faced, ferocious-looking man.
Roa began to notice a pattern: female demons were usually beautiful, while male demons were often ugly brutes.
Without further ado, Roa ended the demon's life with a single strike.
The efficiency of his exploration that night wasn't particularly high. Roa didn't proceed to the next mountain, as the sky was already beginning to lighten.
As the first rays of sunlight pierced through the heavy darkness, daybreak arrived.
The morning air on the mountain was damp, with a faint mist lingering. A gust of wind swept through, rustling the surrounding grass and trees.
Roa yawned and began to make his way back down the path he had come.
However, unlike his journey up, Roa encountered a Hashira on his way back. This Hashira wasn't the Water Hashira but Kocho Shinobu.
She was a girl with black hair, the ends of her bangs tinged with purple, and purple eyes. She wore a butterfly hairpin at the back of her head, primarily mint-colored with deep purple edges. She was dressed in the Demon Slayer Corps uniform, with a haori adorned with butterfly wing patterns draped over it.
Of course, she wasn't alone. She was accompanied by several other members of the Demon Slayer Corps, walking briskly into the distance.
Although Roa was slightly surprised, he didn't show any unusual expression on his face. He simply stepped aside to let them pass.
The girl glanced at the young man, her gaze lingering on him for a moment before she smiled and nodded at Roa, then continued on her way.
Roa returned home and resumed his daily routine: eating, catching up on sleep, and practicing his swordsmanship.
At night, he would go out to hunt demons while continuing his search for Kamado Tanjiro.
And so, the days passed.
In just a week, Roa had scoured the surrounding mountains, killing nearly ten demons, but he still hadn't found any trace of Tanjiro.
Even when he asked the villagers nearby, they claimed they had never heard of such a person.
All signs indicated that his search would likely take a while longer.
Wandering aimlessly, Roa unexpectedly encountered a Lower Moon demon.
This demon was Lower Moon Five, Rui.
He had a head full of white hair, usually covering his left eye, which bore the characters "Lower Five." He wasn't particularly tall, even somewhat short.
When Roa saw him, he was slightly surprised.
But after the initial surprise, he quickly regained his composure.
To be honest, unless it was an Upper Moon demon, Roa was confident he could easily defeat any demon.
The gap between Upper and Lower Moons was vast, and their power levels were worlds apart.
A Hashira could effortlessly kill a Lower Moon.
But an Upper Moon would require two or even three Hashira-level swordsmen to handle.
The higher the level of combat, the greater the disparity.
Naturally, when Roa encountered Rui, the outcome was a swift and decisive victory.
Roa raised his Nichirin Sword high and then brought it down, severing Rui's head in one clean strike.
Rui wasn't always a Lower Moon. He had three family members, forming a twisted demon family.
Roa had no interest in dealing with these pitiful individuals, as their backstories were already well-explained in the original story.
There were many pitiful people in this world, and the existence of demons had destroyed countless families.
Even a swordsman as powerful as Yoriichi Tsugikuni had his wife and child brutally killed by demons.
If there was one evil in the world that must be eradicated, demons were undoubtedly among them.
Demons not only ate humans but also lost their humanity, becoming obsessed with destruction and considering themselves superior beings, treating others as mere snacks.
Naturally, Roa swung his sword and eliminated the remaining three demons.
Brushing the dust off his sleeves, Roa silently mourned for them for a moment before continuing on his way.
However, the news of Lower Moon Four's death eventually reached Muzan Kibutsuji, who immediately sent a message to Gyokko, the nearest Upper Moon, instructing him to investigate.
Although Gyokko's location wasn't too far, it wasn't exactly close either. By the time Gyokko arrived, Roa had already disappeared without a trace.
But this time, Roa's actions had completely exposed his presence.
Roa's exposure was undoubtedly troublesome.
Following his usual routine, Roa didn't return home this time but instead found a random place to stay.
The Demon Slayer Corps had many branch bases, each with its own resting quarters.
These quarters were reserved for the on-duty members of the Demon Slayer Corps.
Roa naturally had the right to stay in them.
Life returned to normal.
Time continued to pass slowly.