Isekai Adventure in the Dimensional Cube

Rengoku Kyoujurou led the mission given by Reiger and left.

He promised Reiger that he would bring back a large amount of Scarlet Crimson Sand Iron and Scarlet Crimson Ore.

The amount of Scarlet Crimson Sand Iron and Scarlet Crimson Ore was substantial; not a single member of the Demon Slayer Corps was without a Sun Wheel Blade. Even Tanjirou received a new one immediately after his broke, which proves that the Demon Slayer Corps weren't lacking in materials for swords. What they lacked were swordsmiths with superior forging skills.

However, this time Reiger did not need anyone to forge a sword for him; he just needed the raw materials for the blades. This request was still not too difficult to fulfill, and Rengoku Kyoujurou said that he would bring back more for him with the lord's permission, showing that he was really considerate.

"Thank goodness the first Pillar I met was from the Rengoku family. Otherwise, it wouldn't have been so easy to talk with anyone else."

Thinking of the other Pillars in the Demon Slayer Corps, Reiger felt more and more that each of them was like a problem child.

In comparison, Rengoku Kyoujurou was just a bit too intense in personality, but he was still very kind-hearted, warm, and friendly towards others.

Entrusting this task to Rengoku Kyoujurou, Reiger also felt at ease.

Thus, Reiger stopped thinking about the Sun Wheel Blades and picked up the compendium of breathing techniques in front of him, starting to read through them one by one.

After about an hour or so, Reiger had gained a substantial understanding of the five basic breathing techniques.

"Although the five fundamental breathing techniques are branches derived from the Sun breathing, each breathing technique has its own characteristics and advantages. If we talk about individual aspects and advantages, they are not inferior to the Sun breathing."

For example, Water Breathing is characterized by its flexibility and variability of sword forms. It is very agile and dynamic in combat, capable of dealing with various battle situations, making it as varied and versatile as flowing water.

Among all the breathing techniques, Water Breathing is comparatively easier to master. It may not be as powerful as other breathing techniques, but it has the advantage in prolonged battles. Even the Sun breathing doesn't have the variability and endurance of Water Breathing.

Ever since the creation of the breathing techniques, Ghost Hunters who mastered Water Breathing have always been the most numerous, resulting in the Water Pillar of the Demon Slayer Corps never having a vacancy.

Therefore, Water Breathing is the first choice for many when it comes to learning breathing techniques. Its ease of mastery and refinement make many Demon Slayer Corps Swordsmen, who don't consider themselves highly talented, inclined to practice Water Breathing.

Flame Breathing is similar in this regard.

It is a breathing technique passed down through generations of the Rengoku Family and is one of the breathing styles closest to the original form of Sun breathing in terms of power. Its might is second to none among all other breathing techniques. Although it is not as easy to learn and master as Water Breathing, Flame Breathing is considered the most complete of all breathing techniques. With diligent study and hard work, once it is mastered, one's strength will increase rapidly and they will quickly stand out.

Like Water Breathing, there has never been a vacancy for a Flame Pillar who masters Flame Breathing. Throughout the history of the Demon Slayer Corps, there has always been both a Flame Pillar and a Water Pillar, cementing these two types of breathing styles as very important within the Demon Slayer Corps.

According to Reiger's estimation, after the Sun breathing, Flame Breathing likely became the second type of breathing technique to emerge. Although it might be less powerful than the Sun breathing, its destructive capability was still formidable.

The remaining three types of breathing techniques each have outstanding features as well.

For instance, Thunder Breathing is considered the fastest and most explosive among all breathing styles, with a speed that could even slightly surpass Sun Breathing, thereby demanding immensely high physical fitness from its users. Next to Sun Breathing, it is incredibly difficult to master, and the current pillars include no one specialized in Thunder Breathing, which speaks to its level of difficulty.

Similarly, Wind Breathing allows every cut made by its practitioners to possess tremendous cutting strength, being the sharpest of all breathing methods. It can easily shear off any part of a demon, and skilled users can even wrap the Wind Blade around their limbs, using this breath style in close combat. Coupled with its speed, which is second only to Thunder Breathing, one can vaguely perceive how powerful a practitioner of this breathing style could be.

And finally, Rock Breathing is quite unique. As the only one among the five basic breathing styles without any derivative styles, it is both stable and robust, excelling in both defense and offense. Practitioners often use heavy weaponry with this breathing style; their defenses are hardly penetrable, and their attacks are weighty and formidable. Those who master it can be said to be invincible.

These five breathing styles, in terms of overall ability, can't match up to Sun Breathing, but if we talk about advantages in specific areas, even Sun Breathing has to admit their superiority.

"Not bad, quite interesting," Reiger commented, clearly engrossed.

Ubuyashiki Kagaya claimed Sun Breathing to be the strongest breathing style, but Reiger was somewhat skeptical.

It really depends on who is using these breathing styles.

Each of the current pillars has mastered their respective breathing styles to the utmost degree. Could someone who casually picks up Sun Breathing defeat any of them?

Impossible.

It's only fair to say that at the same level, someone who has learned Sun Breathing would indeed be stronger than those of other breathing styles, but their strength lies in their comprehensive capabilities.

If both are on the same level, a practitioner of Sun Breathing would neither outlast one who has learned Water Breathing nor outspeed one adept in Thunder Breathing.

Their strikes wouldn't be as sharp as those of a Wind Breathing practitioner.

Their attacks and defenses might also be less formidable than those skilled in Rock Breathing.

Therefore, while Sun Breathing is undoubtedly strong, it is strong in all aspects. When it comes to specialization in a certain area, the five basic breathing styles might not necessarily lose.

In the same vein, derived breathing styles such as Love Breathing, Insect Breathing, Sound Breathing, Water Breathing, and Mist Breathing are merely further specializations based on the original styles. Although they are quite selective with their users, requiring specific talents and special physiques that not just anyone can practice, once mastered, they are no less formidable than the five basic breathing styles and might even be stronger in certain aspects.

However, those few derived breathing styles are indeed quite picky in selecting their users, akin to being severely imbalanced in their specializations, which significantly decreases their reference value for what Reiger was about to do.

"Anyway, let's give it a try," he decided.

After imprinting the five basic breathing styles in his mind, Reiger picked up a training sword that was kept in the room and headed to the courtyard.

...

The process of mastering the five basic breathing styles wasn't too arduous.

Perhaps it was because Reiger's learning ability and growth rate were terrifyingly swift, or maybe because he had already mastered the Sun Breathing technique, the five basic breathing methods derived from it posed little challenge to him, and he easily mastered them.

So...

"Water Breathing·First Form·Surface Slash."

In the courtyard, a ripple suddenly appeared, like a water blade slicing through the surface, instantly cutting through the atmosphere.

Reiger, holding a practice sword, adjusted his breathing. After striking with a flowing water strike, his breathing rhythm sharply changed, turning the water vapor surrounding him into searing flames.

"Flame Breathing·First Form·Fire."

Reiger's form shot forward like a rocket, his body swirling with flames, slashing through the void and then turning to slice and evaporate the water ripple that had just risen.

At this time, Reiger's breathing rhythm changed again, turning the surrounding flames into a whirlwind.

"Wind Breathing·First Form·Dust Tornado·Slicing."

A moment ago he was a rocket, now he was a hurricane.

Reiger's body was enveloped by wind, surging forward, leaving a spiral-shaped Wind Blade behind him that sliced through the earth.

"Rock Breathing·First Form·Feldspar Rock·Dual Polarity."

As the spiral wind blade faded, Reiger's slash was as if it was a massive, dense boulder, stirring up dust and sand as it cleaved through the air.

Finally, when Reiger's toes touched the ground, he shattered the surface beneath him, transforming into a streak of lightning.

"Thunder Breathing·First Form·Thunderbolt Flash."

The sound of thunder tearing through the air rang out as the lightning flash vanished as quickly as it appeared in the courtyard, becoming a fleeting thunderclap as its name implied.

When the flash of lightning dissipated, Reiger's figure appeared amidst the crackling electric current, assuming a sheathing stance.

The complex rhythm of breathing then slowly settled down, and Reiger turned his head to look behind him.

There, the area had become a mess, as if ravaged by artillery fire, with no part left intact.

"...Looks like I'll need to leave some gold for the Rengoku family to repair their courtyard," he muttered, a satisfied expression on his face.

The five basic breathing techniques had thus been mastered by Reiger.

If word of this extraordinary feat were to leak out, it would likely shock many to the point of dropping jaws.

Other people would need several years or even more than a decade to master these breathing techniques to perfection, yet Reiger did it with ease, and all five of them at once.

If the Pillars knew about this, they would likely be devastated.

However, for Reiger, the real work was just beginning.

"I wonder if it will work out as I wish?" he murmured to himself.

"Using the Sun Breathing as a foundation, integrating the breathing techniques of the Demon Slayer World with the swordsmanship of the Continent of Akasha."

Yes, that was what Reiger planned to do in this world.

Upon learning that this Dimensional Travel led to the Demon Slayer World, Reiger immediately thought of combining the breathing techniques of both worlds.

"The breathing techniques of the Demon Slayer World involve drawing in large amounts of oxygen to enhance cardiopulmonary function and accelerate blood flow, momentarily granting the user superhuman strength."

"The swordsmanship of the Continent of Akasha, on the other hand, uses breathing techniques as an aid to stimulate Magic Power, energizing the flesh and allowing the body to absorb Magic Power and grow stronger."

"So, what if I were to merge these two principles of breathing and incorporate sword skills from both worlds? Could I obtain a perfect mix, a power that boosts strength during combat and allows one to grow stronger with each use?"

"Furthermore, could I enhance not just the cardiopulmonary functions and accelerate blood flow, but also strengthen every organ and every cell, merging the energized, potent Magic Power into the accelerated blood flow to unleash an astonishing combat power?"

This was Reiger's idea: to fuse the principles of breathing techniques and swordsmanship from both worlds, creating a fighting style that allowed him to explode in power during battle and grow increasingly stronger with each fight.

Should he succeed, it would be a sword skill superior to the perfectly mastered Holy Dragon Sword Skill.

After all—

"Becoming a dragon is exhilarating, but becoming the sun is even more thrilling, isn't it?" Reiger's eyes sparkled with enthusiasm, and his lips curved into a smile.