What I gained from Gyutaro was a Blood Demon Art called Blood Demon Art: Batsu Arc Jumping Beam, a technique that surrounds the user with slicing waves of blood for defense.
Raiden did not integrate this Blood Demon Art simply for its offensive ability. He already had plenty of ways to deal damage. Instead, he absorbed it for the realm improvement it could grant him.
After stretching, Raiden prepared to integrate both Sound Breathing and the Blood Demon Art.
"Do you choose to integrate Sound Breathing Fourth Form: Resounding Slash of No Interval (Mastered) now?"
"Yes."
Raiden sat on the simple tatami mat, closed his eyes, and adjusted his breathing. A barely visible airflow began to pulse around him.
As soon as he committed, a subtle change began within his body, like tiny musical notes dancing in his blood. Every cell responded, synchronizing to the rhythm.
His breathing slowly aligned with Uzui Tengen's unique Sound Breathing, as though he could hear the melody and tempo behind every breath.
During this process, his mind became extraordinarily clear. He sensed every detail of Sound Breathing Fourth Form, and the path of each sword movement seemed to be rehearsed in his imagination.
His inner world became serene yet vibrant, like a complex score revealing its secrets one measure at a time.
As time passed, Raiden entered a remarkable state. His body repeated the movements of Sound Breathing automatically, and each breath seemed to gently move the air around him, producing a quiet resonance.
Every internal change was filled with power and rhythm, like a musician playing perfect notes on an instrument.
When the integration was complete, Raiden felt a refreshing rush of excitement and satisfaction.
What a strange process. Integrating Sound Breathing brought no discomfort at all. It was like listening to an elegant and uplifting song until the final note faded.
He felt the improvement this style gave him. It was real, yet not major. He still had far to go before breaking through to the Middle Pillar level.
Raiden's feelings stayed calm. The Sound Pillar's strength was average among the Nine Pillars, and he had expected modest gains.
"Do you choose to integrate Blood Demon Art: Batsu Arc Jumping Beam (Mastered) now?"
"Yes."
He twisted his wrists and began integrating Gyutaro's Blood Demon Art.
The moment the process started, Raiden felt his blood ignite. Every vessel pulsed with power. His body trembled and heat surged through him. That was the sensation of the Blood Demon Art taking shape inside him.
This feeling had happened before when integrating Akaza and Doma's demon arts. His blood seemed alive, flowing along mysterious paths.
In Raiden's mind, he saw Gyutaro performing the Batsu Arc Jumping Beam. The image of Gyutaro's lithe, airborne form came into view—every movement full of strength and grace.
A strange synchronization washed over him. He sensed Gyutaro's calm focus as though it were his own.
He watched the moment Gyutaro launched into the attack. Raiden saw the rapid flexing of muscles in the leg, as powerful as a fully drawn bow, transmitting force through the body in the most efficient way.
To him, those muscles weren't simple tissues anymore. They were optimal units of force, each contraction perfect, without waste.
Even subtler was the twist of the waist and flex of the spine. Raiden felt the faint vibrations of Gyutaro's core muscles adjusting in midair, the key to balancing his body.
It was like watching power flow through the spine as if it were living water leaping along a riverbed, reaching every part of the body.
When Gyutaro finished using Batsu Arc Jumping Beam, the integration process ended as well.
The realm enhancement Raiden gained from this Blood Demon Art was significantly greater than from Sound Breathing. He was now closer than ever to breaking through to Middle Pillar, something expected in the next few days.
Once he reached Middle Pillar, Doma wouldn't be a viable opponent anymore. Even if Doma tried to flee, escape wouldn't be possible.
After the Entertainment District battle, Raiden's desire to grow stronger had only intensified.
He knew that killing Rui and repelling Akaza would draw Muzan's attention. What he didn't expect was just how much of it it would attract.
Where Upper Moon Six was supposed to appear, Doma had been brought along too.
Because of that experience, Raiden felt certain the upcoming Swordsmith Village incident wouldn't play out the same as the original timeline.
In the original Swordsmith Village incident, Gyokko and Hantengu were supposed to show up.
But now, with his presence in the world, Raiden had a hunch the situation would be very different.
If Doma and Akaza arrived, that might still be manageable since Raiden was already stronger. With Transparent World activated, whoever came—Doma or Akaza—would die.
Yet if Kokushibo appeared, things could be much worse. Kokushibo didn't just have a complete Transparent World, he also possessed Speckles Enhancement.
In the Infinity Castle, Kokushibo had fought the Stone Pillar, Wind Pillar, and Genya Shinazugawa by himself.
Facing such a foe with Raiden's current strength would be extremely difficult. Even if he reached Middle Pillar, it was unlikely he could defeat Kokushibo.
Raiden knew he had to complete the remaining steps of Transparent World and then master Speckles and the Crimson Blade to stand a chance.
Speckles was manageable. Tanjiro had already activated Speckles in the Entertainment District battle. Even if Raiden and Tanjiro's connection was temporarily plateaued, Raiden could still learn Speckles from Tanjiro thanks to his superior comprehension.
The Crimson Blade was more complicated. Tanjiro had only barely accessed it during his fight with Hantengu with the help of Nezuko's blood.
That situation was unique, and Raiden wasn't sure whether the same conditions applied to him.
After all, Snake Pillar Obanai and Mist Pillar Muichiro had awakened the Crimson Blade without Nezuko's blood. They had only unleashed it when their backs were against the wall.
"I'll watch carefully how Tanjiro uses the Crimson Blade during the Swordsmith Village arc. For now, my focus must be on perfecting Transparent World and building my strength."