"NO! I HAVEN'T LOST YET!"
As soon as Raven's yell erupted, a blinding black light burst from his body, plunging the entire training field into darkness.
"Wh-What happened?!"
Such a sudden darkness threw the entire training field into chaos, causing the onlookers to panic, restless, and uneasy. Some instinctively cast magic for illumination, but the moment the light appeared, it was immediately sucked away, vanishing as if devoured—no one knew what was happening.
"Don't panic!"
"Calm down!"
"All of you, this is the swordsmanship of the Mavros family! Just stay calm!"
Kaiser, Axel, and Diego, who were familiar with the Mavros family's swordsmanship, shouted from where they stood to calm everyone down.
Nibald was also trying to reassure Lizbeth, who was flustered beside him.
"Calm down, this is the Special Swordsmanship of the Mavros family, Dark Abyss Sword Style, not some kind of anomaly."
Dark Abyss Sword Style.
It was the inherited swordsmanship of the Mavros family, personally developed by Raven himself—a Special Swordsmanship he created after dedicating his entire life to its mastery.
When Raven was young, he wasn't a noble but a wandering swordsman who initially studied an Advanced Swordsmanship he happened to acquire, unlike those nobles who could effortlessly inherit Special Swordsmanship from their families.
Back then, after reaching the limit of Sword Master, Raven realized that his swordsmanship alone wasn't enough to push him further toward the realm of a Sword Saint. Determined to surpass his limits, he traveled across Jinas, gathering and studying countless forms of swordsmanship over several years. After relentless research and refinement, he finally succeeded in creating a Special Swordsmanship called the Dark Abyss Sword Style.
With this swordsmanship, Raven ascended to the rank of Sword Saint ten years ago and was granted nobility. Later, after continuously making achievements on the battlefield, he finally became a marquis.
From then on, the Dark Abyss Sword Style became the Mavros family's inherited swordsmanship, allowing Kaiser, Axel, Diego, and the other direct descendants of Raven to learn the Special Swordsmanship personally created by him.
What made Raven's swordsmanship unique was that it could absorb external powers and transform them into power for its users.
For example, when Riezel infused his invitation letter with the power of Thunder Breathing and hurled it at Raven, Raven activated the Dark Abyss Sword Style, absorbing the aura emanating from himself and converting it into power, neutralizing the power of Thunder Breathing within Riezel's invitation letter.
Similarly, before their fight began, Raven had also used the Dark Abyss Sword Style, causing waves of dark energy to rise from his body as if devouring everything around him.
Needless to say, that dark energy was the power of the Dark Abyss Sword Style.
Raven could use this swordsmanship to absorb his own aura, magical energy, and even elements like air, light, and poisons, converting them into the dark energy he controlled.
Moreover, this dark energy could be used both offensively and defensively, increasing Raven's striking power when used for attacks and heightening his resistance when used for defense. If wielded skillfully, it could even cancel out Riezel's attacks, just as Raven had done earlier when he had rendered Riezel's lightning slash completely ineffective.
In terms of versatility and practicality, the Dark Abyss Sword Style undoubtedly ranked among the top three Special Swordsmanships in all of Jinas—if not competing for first or second place.
Its most remarkable trait was that the more external powers it absorbed, the stronger it became.
Right now, Raven had clearly pushed the Dark Abyss Sword Style to its limit, absorbing all the light from the training field and plunging it into complete darkness.
"HAAAAAAHHHHHH—!!!"
Raven's roar echoed across the training field, making even Riezel, who had lost his vision, clearly sense a terrifying power taking shape.
Riezel activated the Transparent World without hesitation, making his eyes take on a transparent glow as he focused in Raven's direction.
Over there, Raven had already risen to his feet, roaring as a dense and astonishing surge of dark energy wildly swirled around him. Like a raging darkness, it formed a pitch-black storm around his body, continuously expanding.
Gathering the overwhelming dark energy into the greatsword in his hand, Raven merged the mysterious glow on its blade with the dense darkness, unleashing an incredibly terrifying power.
Seeing this scene, Riezel didn't rely on thought since he understood instinctively that Raven's next strike was going to be extraordinary.
Realizing this, Riezel's eyes flickered before his mouth curled into a smile.
"Not bad."
Riezel's voice was no longer calm since it carried a hint of his natural excitement as it spread through the air.
"In that case, guess I'll get a little serious and show you a sword form no one's ever seen before."
As soon as these words left Riezel's mouth, he slowly closed his eyes.
By this point, Riezel had already come to a realization.
'Seems like the usual breathing styles won't do much for me anymore...'
It was inevitable.
Breathing styles, which were unique swordsmanship from the world of Demon Slayer, were without a doubt profound swordsmanship, capable of fully drawing out the human body's potential, transforming an ordinary person into an extraordinary warrior able to stand against demons.
Riezel had to admit, breathing styles were a miracle.
However, when it came down to it, the world of Demon Slayer wasn't a world with a particularly high power level—in fact, its limits were relatively low.
In that world, even swordsmen who mastered a breathing style and reached the rank of Hashira were only roughly equivalent to Level 4.
Kokushibou, who practiced Moon Breathing, reached Level 5 only after becoming a demon, while Level 6 was reached by only two individuals—Tsugikuni Yoriichi and Kibutsuji Muzan, the strongest beings in that world.
Putting aside Muzan, who originally wasn't human, the only human who had truly transcended through a breathing style, reaching a level comparable to a Sword Master on the Akasha Continent or a First-Class Adventurer in the world of Danmachi, was only Yoriichi.
However, the reason Yoriichi reached such a realm likely had more to do with his unique traits rather than his breathing style.
One should know that he was revered as a being akin to a god because of his astonishing potential. He was born with the Demon Slayer Mark, instinctively understood the principles of breathing styles, and awakened the Transparent World and the Selfless State entirely on his own—things no ordinary person could ever achieve.
Simply put, Sun Breathing was only a part of Yoriichi's power, which undoubtedly contributed to his strength, but it wasn't the sole reason he was powerful.
In the original work, Tanjirou eventually learned Sun Breathing as well, but even after mastering it, the strongest he ever got was on par with the Hashira.
Moreover, the reason he managed to ultimately defeat Muzan wasn't because of Sun Breathing alone but thanks to the support of countless members of the Demon Slayer Corps, the sacrifice of numerous Hashira, and even the life-risking assistance of a demon like Tamayo, which was what led to the final victory.
Compared to Yoriichi, who could defeat Muzan alone, Tanjirou didn't even come close.
Even if Tanjirou dedicated his entire life to studying Sun Breathing, he would never reach Yoriichi's level. Not to mention, in the original work, Tanjirou also awakened the Demon Slayer Mark—meaning he wouldn't even live past twenty-five.
Meanwhile, Yoriichi, the creator of the breathing style who was born with a Demon Slayer Mark, had lived well into his eighties and had even almost managed to cut down Kokushibou, who had already turned into a demon by then.
All of this showed that Yoriichi's ability to reach the strength equivalent of Level 6 was largely due to his own unique traits.
And yet, even Yoriichi hadn't managed to reach Level 7 while he was alive. It wasn't until after his death, when he gained insight from Riezel's training, that he evolved his Sun Breathing and successfully stepped into Level 7.
Under these circumstances, the upper limit of regular breathing styles was naturally low because raising an ordinary person to Level 4 was already close to their limit. If someone had other fortuitous encounters, they might still be able to use it at Level 5 or Level 6, but once they reached Level 7, the effectiveness and power of breathing styles would significantly weaken.
At Level 7, the human body had already reached an almost unimaginable level of strength, so how could a body like that still be enhanced just by absorbing a large amount of air?
It just wasn't possible.
Because of this, after Riezel reached Level 7 and his body had been elevated to an extremely high degree, regular breathing styles could no longer bring him any noticeable improvements.
Back at Level 6, when he had just leveled up, Riezel could already surpass the limit of Level 6 in his normal state, while when using Thunder Breathing and other breathing styles, he could even go beyond Level 6 and compete against beings equivalent to Level 7.
However, now, after reaching Level 7, while his normal state still surpassed the limit of Level 7, using Thunder Breathing and other breathing styles no longer allowed him to challenge higher levels.
Of course, this wasn't just because it became harder to surpass levels the higher one went but also because regular breathing styles like Thunder Breathing no longer provided him with a significant strength improvement.
At this point, only two breathing styles still had a noticeable effect on him.
One was the evolved Sun Breathing, while the other was Wind Breathing, which complemented the extraordinary enchant-type magic, Ariel.
As for the rest, even Moon Breathing, which was the most compatible with Riezel after Sun Breathing, no longer had much of an impact on him. He could already imagine that once he reached Level 8, all breathing styles except Sun Breathing and Wind Breathing would completely lose their ability to strengthen him.
However—
'Even if the strengthening effect from breathing styles fades, my attacks still carry their traits when I use their sword forms.'
Indeed, when Riezel used 'Thunderclap and Flash', his speed and explosive power would still be incredibly strong because the essence of this sword form was extreme speed and extreme explosiveness, so naturally, the same logic applied to Moon Breathing.
Even though Moon Breathing might no longer enhance his strength in the future, its sword forms, which possessed an incredibly wide attack range, would still be useful since they would allow him to continue unleashing powerful AoE attacks in battle.
Because of this, not only did he not abandon Thunder Breathing, but as he continued to study Sun Breathing's thirteenth sword form, Blooming Radiance, he also completed one of the most powerful sword forms of Thunder Breathing.