After chatting for a while, Kyoujurou finally left to fulfill Riezel's request. He promised Riezel that he would bring a large amount of Scarlet Crimson Iron Sand and Scarlet Ore.
It was not weird for Kyoujurou to make such a promise since there remained a considerable quantity of Scarlet Crimson Iron Sand and Scarlet Ore, as no member of the Demon Slayer Corps lacked a Nichirin Sword.
Even Tanjirou, whose Nichirin Sword had been broken once, quickly acquired a new one, demonstrating the availability of materials for the swords.
What was likely in short supply were swordsmiths with exceptional skills.
However, since Riezel didn't need someone to provide swordsmithing, he just needed the raw materials for the sword, which wasn't difficult.
Kyoujurou expressed that he would try to bring back as much as possible after obtaining permission from Kagaya, which was quite thoughtful of him.
'Fortunately, the first Hashira I got to know was Rengoku. Otherwise, if it were someone else, it wouldn't be so easy to talk to...'
As Riezel thought of the other Hashira in the Demon Slayer Corps, he increasingly felt that each one of them was a problem child. In comparison, even though Kyoujurou had a unique personality, he was still very kind-hearted and friendly toward others.
As such, handing this matter over to Kyoujurou, Riezel felt at ease.
Shaking his head, Riezel stopped thinking about Nichirin Sword and picked up the five books of breathing styles in front of him, starting to read through them one by one.
After about an hour of reading, he had a certain understanding of the five fundamental breathing styles.
'Although the five fundamental breathing styles are all derived from Sun Breathing, each of these breathing styles has its own characteristics and advantages. If I only consider their individual characteristics and advantages, they are not inferior to Sun Breathing.'
For example, Water Breathing, characterized by its softness and versatile sword forms, was very dexterous and agile in combat, able to deal with various situations. It was a breathing style as changeable as flowing water.
Among all the breathing styles, Water Breathing was rather easy to practice. Perhaps it didn't have the same power as the other breathing styles, but it had the most advantage in prolonged battles. Even Sun Breathing couldn't match the versatility and endurance of Water Breathing.
Since the birth of breathing styles, Demon Slayers proficient in Water Breathing had always been the most numerous, resulting in never having a vacancy for the Water Hashira.
Because of this, Water Breathing was the preferred choice for many when practicing breathing styles. Its characteristics of being easy to practice and easy to master made many Demon Slayers who didn't consider themselves very talented inclined to practice Water Breathing.
Similar to Water Breathing was Flame Breathing.
This was a breathing style passed down through generations in the Rengoku family, and it was the breathing style closest to Sun Breathing, as its power ranked among the top of all breathing styles.
Although it wasn't as easy to practice and master as Water Breathing, Flame Breathing could be considered the most comprehensive of all breathing styles. With diligent study and effort, once mastered, the user's strength would increase rapidly and they would quickly rise to prominence.
Just like Water Breathing, there had never been a vacancy for the Flame Hashira.
As a result, throughout the generations of the Hashira, both Flame Hashira and Water Hashira have always existed, maintaining the significant presence of these two breathing styles within the Demon Slayer Corps.
According to Riezel's speculation, initially, after Sun Breathing, the second breathing style to be born was probably Flame Breathing. Compared to Sun Breathing, it might not be as powerful, but its destructive power was still very strong.
Despite that, the remaining three fundamental breathing styles also had outstanding characteristics.
For example, Thunder Breathing was considered to be the fastest among all breathing styles, with the strongest explosive force, even surpassing Sun Breathing in terms of speed alone.
For this reason, it demanded extremely high physical qualities from its users, second only to Sun Breathing. It was extremely difficult to practice, as evidenced by the absence of Hashira proficient in Thunder Breathing, indicating the difficulty of mastering it.
Another example was Wind Breathing, which granted each slash of the user a very powerful cutting power, making it the sharpest breathing style.
Not only it could easily slice off any body part of demons, but proficient users could even wrap wind blades around their hands and feet, using this breathing style as Taijutsu. Coupled with its speed second only to Thunder Breathing, the strength of those who practiced this breathing style could be vaguely imagined.
Lastly, Stone Breathing was particularly unique.
As the only breathing style among the five fundamental breathing styles without derived branches, not only it was both stable and heavy, but it also excelled in defense and offense alike.
Users of this breathing style often used heavy weapons, making their defense impregnable and their attacks powerful and forceful. Those who were proficient in it could be considered invincible.
Overall, these five fundamental breathing styles, in terms of overall ability, fall short of Sun Breathing. But if one considered only a specific ability, even Sun Breathing would have to admit defeat to them.
"As I thought, they're quite interesting..." Riezel muttered with relish.
When Kagaya claimed that Sun Breathing was the strongest breathing style, Riezel was somewhat skeptical. After all, it still depended on the person who used it.
Among the current Hashira, each one had honed their respective breathing styles to peak proficiency. If going according to Kagaya's logic, didn't that mean anyone who practiced Sun Breathing could defeat them?
Impossible.
It could only be said that if they were at the same level, then indeed, the one who practiced Sun Breathing would be stronger than those who practiced other breathing styles.
But in the end, their strength still lay in their own overall ability.
Even if both sides were at the same level, the one who practiced Sun Breathing wouldn't have more endurance than someone who practiced Water Breathing, nor would they be faster than someone who practiced Thunder Breathing.
Plus, their slashes wouldn't be as sharp as those who practiced Wind Breathing, and perhaps, their offensive and defensive strength might even pale in comparison to someone who practiced Stone Breathing.
Therefore, while Sun Breathing was indeed powerful, its strength lay in being versatile. Compared to the specialized capabilities of the five fundamental breathing styles, it may not necessarily win.
Similarly, breathing styles derived from fundamental breathing styles like Love Breathing, Insect Breathing, Sound Breathing, Serpent Breathing, and Mist Breathing specialize even further in certain aspects than their origins.
Although they were picky about their users and couldn't be practiced without corresponding talents and special physical qualities, once mastered, they were no less inferior to the five fundamental breathing styles, and in some aspects, even stronger.
However, breathing styles derived from fundamental breathing styles were really picky about their users, like focusing too much on one aspect, which diminished their value for what Riezel was about to do.
"In any case, let's give it a try."
After memorizing all the five fundamental breathing styles, Riezel picked up a practice wooden sword placed in the room and headed to the courtyard.
===
Mastering the process of five fundamental breathing styles wasn't too difficult.
Perhaps it was due to Riezel's own terrifying learning ability and growth speed, or perhaps it was because he had already mastered Sun Breathing, the five fundamental breathing styles derived from Sun Breathing posed little difficulty for him and were easily mastered.
As a result—
"Water Breathing - First Form - Water Surface Slash."
In the courtyard, a wave of water suddenly appeared, like a water blade slashing through the air, instantly cutting through the air.
With a practice sword in hand, Riezel adjusted his breathing. After slashing a stream of water in front of him, the rhythm of his breath suddenly changed, causing the water vapor around him to turn into flames.
"Flame Breathing - First Form - Unknowing Fire."
Riezel dashed forward like a rocket, engulfed in flames. After slashing through the air, he turned back and cut off the water waves that had just risen, evaporating them.
In the next moment, Riezel's breathing rhythm changed again, turning the flames around him into a whirlwind.
"Wind Breathing - First Form - Dust Whirlwind Cutter."
Just a moment ago he was a rocket, now he was a hurricane.
Covered in wind, Riezel surged forward, leaving behind a spiral wind blade that cut through the earth.
"Stone Breathing - First Form - Serpentinite Bipolar."
As the spiral wind blade disappeared, Riezel's next slash was as heavy as a giant rock, stirring up rebellious dust as it passed through the air.
Finally, as his foot touched the ground, he shattered it, transforming into a lightning ray.
"Thunder Breathing - First Form - Thunderclap and Flash."
As the sound of thunder ripping through the air echoed, a lightning ray flashed in the courtyard, just as the name implies, becoming a fleeting thunderclap.
When the lightning ray disappeared, Riezel's figure appeared amidst the crackling lightning current, assuming an Iai stance.
Gradually, the ever-changing rhythm of his breathing calmed down, allowing him to turn his head and look behind him.
There, the surrounding terrain had become a mess, like it had been ravaged by artillery fire, with not a single intact spot.
"Looks like I'll have to leave some gold for Rengoku to fix his courtyard later..." Riezel muttered, a satisfied expression on his face.
And just like that, he finally mastered the five fundamental breathing styles.
Such a sensational and astonishing feat, if word got out, it would surely shock many people to the core.
While it took others several years, or even a decade, to master one breathing style, Riezel effortlessly mastered not just one, but five at once. If the Hashira found out about this, their will would likely be utterly crushed.
However, for Riezel, the real deal was just beginning.
"I wonder if it can be as I wish..." Riezel murmured. "Using Sun Breathing as the foundation, integrating the swordsmanship of this world with the swordsmanship of Akasha Continent."
Yes, that was what Riezel intended to do in this world.
Upon learning that this dimensional travel was to the world of Demon Slayer, Riezel immediately thought of the breathing techniques and swordsmanship of both worlds.
'If I'm not wrong, this world's swordsmanship is called 'Breathing Style' because it uses a unique breathing technique known as 'Total Concentration Breathing' as its main method to strengthen the heart and lungs by absorbing a large amount of air, accelerating blood flow, temporarily granting strength beyond human limits.'
'On the other hand, the swordsmanship of Akasha Continent uses breathing as a support, stimulating and activating magical energy within one's body, making it absorb magical energy to become stronger.'
'In that case, if I incorporate the breathing technique principles and the swordsmanship from both worlds, wouldn't I create a perfect blend that not only boosts my strength during combat but also makes me stronger after each use?'
'Moreover, can I not only make it accelerate my blood flow and strengthen my heart and lungs, but also enhance every organ, even every cell, by infusing them with my massive amount of magical energy, thus unleashing astonishing strength?'
Such was Riezel's plan—to merge the breathing technique principles and swordsmanship from two worlds, creating a combat style that allowed his strength to explode during combat and become stronger with each battle.
Once achieved, it would be a special swordsmanship surpassing even the complete Holy Dragon Sword Style.
After all—
'Who needs to become a dragon when becoming a sun is more exciting?'
Riezel's eyes sparkled as a smile formed at his mouth.