Sakonji silently watched Sol Mirek, his expression hidden behind the Tengu mask. The crackling fire sounded unusually loud inside the quiet hut.
"So, Nezuko is the perfect form Muzan dreams of?" Sakonji asked. His voice was low and hoarse.
Sol nodded slightly.
"You could say that. However, her current state is still unstable. She needs time to grow."
Urgent footsteps approached from outside.
The door burst open as Tanjiro stumbled inside, drenched in sweat.
"I... I'm back!" he gasped, a victorious smile on his face.
Sakonji stood and walked over to him.
"An hour earlier than I expected."
Tanjiro forced himself to stand straight. Determination burned in his eyes.
"I promised to protect Nezuko. That means I must become stronger."
Sol leaned casually against the wall, the corner of his mouth lifting slightly. The boy's growth rate was impressive.
"Rest for now," Sakonji said as he turned toward the door.
"Formal training begins tomorrow. I acknowledge you, Kamado Tanjiro."
Tanjiro nodded heavily.
A moment later, exhaustion claimed him. He collapsed onto the floor and fell asleep almost instantly.
Sol walked over, lifted him carefully, and placed him on the bed beside Nezuko.
He then moved to the window. Moonlight spilled through the wooden frame, casting soft shadows across his face.
Tanjiro slept deeply, still holding Nezuko's hand.
Even in his sleep, he refused to let go.
"Aren't you going to rest?" Sakonji asked from behind him.
The Tengu mask glowed faintly red in the firelight.
"No need," Sol replied calmly.
"I want to look at this world's moon."
"This world's moon..." Sakonji repeated softly as he stepped beside him.
The two stood in silence, staring out the window.
Moonlight spread across the mountains like flowing silver mist. In the distance, faint bird calls echoed through the forest.
After a long pause, Sakonji finally spoke.
"Are you from another world?"
The question had been on his mind for a long time.
Since Sol had already revealed strange knowledge, it was clear he had not intended to hide the truth.
He wanted to know what another world looked like.
Did demons exist there too?
Sol did not answer immediately. His eyes remained fixed on the moon.
After a moment, he spoke quietly.
"Yes."
"It is a world without demons."
"A peaceful place."
A trace of melancholy crossed his mind.
He did not know how strong he needed to become to return home. Even though he had once felt a sense of belonging somewhere else, he knew he never truly belonged to that world either.
Sakonji's eyes widened slightly beneath the mask before returning to calm.
"So that is why you know so much about Muzan."
"Something like that," Sol replied.
"You can understand it that way."
He walked to the corner of the hut, sat cross legged, and closed his eyes to rest.
Morning sunlight streamed through the wooden window.
Tanjiro suddenly opened his eyes.
He found himself lying on the bed, while Nezuko rested inside her bamboo basket nearby.
"Awake?"
Sol's voice came from the doorway.
He leaned against the doorframe, lazily swirling tiny currents of air around his fingertips. It was the result of combining psychokinesis with breathing techniques.
He had already proven something interesting.
If a Nichirin blade could conduct energy through breathing techniques, then an ability that belonged to the body itself should conduct energy even better.
Compared to that, the Demon Slayer Corps seemed overly conservative. They lacked the curiosity needed for real experimentation.
Now Sol could use psychokinesis to perform Water Breathing, while his body could perform the same technique independently.
The two effects were different, yet strangely compatible.
Psychokinesis shaped the air like flowing water.
When combined with Water Stream Rock Smashing Fist, the effect became even smoother.
Tanjiro quickly sat up.
"Mr. Sol! How did I..."
"You passed out from exhaustion last night," Sol replied.
He stepped inside the hut.
"Sakonji said formal training begins today."
Tanjiro jumped out of bed.
Unfortunately, he kicked the bedpost and winced in pain.
Sol watched the clumsy movement, amused.
"No need to rush. He went to prepare breakfast."
Just then, the door slid open.
Sakonji entered carrying a pot of steaming porridge.
"If you're awake, come eat."
After breakfast, the three walked to the open clearing behind the hut.
Sakonji handed Tanjiro a katana.
Originally, he had prepared one for Sol as well.
In the end, he decided not to give it to him.
The sword he prepared probably was not even as durable as Sol's own hands.
"Tanjiro, begin with basic swings."
Sakonji led him toward a straw training bale.
"A sword handles vertical force well, but horizontal force is far weaker. Because of that, your power must move in a straight line."
"The direction of the blade and the direction of the force must match perfectly."
"If the sword breaks, your bones will break as well. Do you understand?"
"Yes!"
Tanjiro gripped the katana firmly with both hands and began practicing the basic swing under Sakonji's guidance.
"Your breathing must match your movement," Sakonji instructed.
"Inhale to gather strength. Exhale when you swing."
Tanjiro adjusted his breathing rhythm.
Slowly, his movements became smoother and more controlled.
Satisfied that Tanjiro had found the rhythm, Sakonji walked over to Sol, who rested with his eyes closed.
Sol opened his eyes and stood.
"I'm ready."
"Good," Sakonji said with a nod.
"I will now explain my full understanding of Water Breathing."
"Compared to other breathing styles, Water Breathing is gentle. However, it requires a calm mind. Your heart must remain as still as water."
"Once mastered, your slashes will flow like a river."
Sakonji demonstrated the technique once in front of him.
When the demonstration ended, Sol immediately adjusted his breathing rhythm.
With his control over his own body, it was effortless.
His heart rate accelerated dramatically.
His body temperature rose rapidly, easily surpassing thirty nine degrees Celsius.
Yet it continued climbing.
For Sol, this level was trivial.
At the same time, his heart rate surged past two hundred beats per minute.
For most Demon Slayer Corps members, such strain would cause severe damage, drastically shortening their lifespan. Few survived past twenty five.
For Sol, however, it meant almost nothing.
His body could endure far more.
This was nowhere near his limit.
Sakonji stared at him with quiet shock.
Sol's upper body was bare, revealing faint wave shaped patterns across his skin.
His breathing became incredibly steady.
Each inhale seemed to draw in the surrounding air.
Each exhale rolled outward like a powerful tide.