A Departed Soul's Entrustment

Tanjiro's Kagura dance was still somewhat unpolished, yet it contained an ancient rhythm. Like a key, it opened an entirely new door for Kashu.

He immersed himself in researching Breathing Styles, neglecting food and sleep.

Hinokami Kagura was undoubtedly a Breathing Style.

It was a miraculous technique capable of drawing forth heat like that of the sun, amplifying the body's abilities far beyond imagination.

Afterward, combining what Tanjiro had told him with repeated study of the Ubuyashiki clan's ancient records, Kashu further confirmed his own conjecture—

Sun Breathing, marks, shortened lifespan...

Just a few words, yet they pointed to the strongest inheritance that had long been lost.

Using the Kagura dance as its skeletal foundation, he would reverse-engineer and merge the essence of the five fundamental Breathing Styles.

A path belonging to Kashu alone was slowly being forged.

Time passed, and the injured gradually recovered.

Tanjiro, having recovered early, would always return to the Butterfly Mansion during breaks between missions to visit his companions and Kashu as well.

Through their repeated close encounters, his extraordinary sense of smell caught the astonishing transformation in Kashu.

It was no longer merely a scent, but an invisible aura. Simply approaching him was enough to make one's chest tighten and breathing grow difficult.

It was like facing a prehistoric dragon lying dormant in false sleep, with every inch of space radiating destructive pressure.

Reason told Tanjiro that Mr. Kashu was not an enemy.

Yet the warning deep within his very being blared madly, urging him to stay away from this dangerous person!

One morning, Tanjiro first went to visit his companions, delighted by their recovery and progress.

Then, as usual, he entered the small courtyard where Kashu often stayed.

The sight before him made his pupils contract sharply. The once-level rehabilitation grounds were now completely unrecognizable.

The ground was covered in savage craters, their edges blown apart.

Long, narrow cracks spread like a spiderweb, their depths unfathomable.

The left side was soaked in mud, as though a torrential rain had just fallen.

The right side was charred black, as if it had been scorched repeatedly by raging flames.

Boom!

Accompanied by a dull, thunderous blast, Kashu's figure appeared at the center of the grounds.

"Hiss—"

The sound of incomparably efficient breathing reached him. The surrounding air warped from the intense heat, and billowing waves of heat rushed toward his face.

Tanjiro instinctively raised a hand to wipe his face. His palm came away drenched in sweat, and even his lips felt painfully dry and scorched.

"Mr... Mr. Kashu?"

Tanjiro's voice trembled.

In an instant, the suffocating pressure vanished like smoke, as if it had never existed.

Kashu slowly turned around, his gaze calm.

"Your mission's over?"

Tanjiro immediately straightened his back and reported.

"Yes! I've slain the demon on South Street!"

Kashu nodded slightly as he assessed him.

"Actual combat is the best tempering. Compared to two months ago, your body has become much tougher."

He casually dismissed his longsword. As he passed Tanjiro's side, his steps paused briefly.

"With your current physical condition, you still can't use Hinokami Kagura for extended periods."

"Water Breathing is easy to learn, but it has also restrained you. When you have the chance, try familiarizing yourself with Flame Breathing."

Before his words had even faded, Kashu had already headed toward the lounge, leaving Tanjiro standing alone to process what he had heard.

Only then did Tanjiro belatedly fall into stunned disbelief.

The terrifying aura around Mr. Kashu... had disappeared?

Inside the lounge.

Fou, who had been idling away in boredom, sensed the change in Kashu's presence. A sharp glint flashed through its beastly eyes before it resumed its innocent, adorable appearance.

Kashu noticed none of this. He merely stared blankly at his own palm.

Casting aside all superfluous thoughts, he focused his senses to their utmost limit.

The flesh-and-blood body before his eyes seemed to shed its outer shell, becoming clear and transparent.

Blood surged like rivers, bones locked tightly together, and even the twitch of every muscle fiber was visible with perfect clarity.

This was the Transparent World Tanjiro's father had once mentioned.

The supreme realm of seeing through the essence of all things and reaching straight to their core.

In this state, every fraction of the body's strength could be mobilized with absolute precision.

Any technique became effortless, while an enemy's movements and intentions had nowhere to hide.

More importantly, this ultimate control allowed him to perfectly conceal the aura overflowing from his training.

That was why Tanjiro had felt the oppressive pressure around him vanish earlier.

But Kashu had only just glimpsed the threshold. For now, he could not maintain the Transparent World for long.

The mental burden steadily increased, and ringing ears and a burning head overwhelmed him.

He immediately adjusted his breathing rhythm, and his heart began to pound powerfully.

The newly generated magic power surged through his bloodstream into every limb and bone, nourishing and strengthening his body as the discomfort slowly faded.

Kashu let out a long breath, anticipation gleaming in his eyes.

"Next, I'll master Total Concentration: Constant."

Maintaining his breathing and turning it into instinct was not difficult for him.

Kashu closed his eyes and began adapting to an all-day breathing rhythm.

The sun rose and the moon set; the stars turned overhead.

After a full day and night, Total Concentration: Constant had completely fused into his every heartbeat and breath.

Yet the instant his awareness returned, Kashu discovered in astonishment that he was no longer in the Butterfly Mansion.

Instead, he stood in an endless expanse of pure white, so silent it made his heart uneasy.

"This is..."

Jingle, jingle—!

A crisp ringing drifted toward him on the wind from behind. Kashu spun around sharply.

In the distance stood a man dressed in a fiery red haori, his long hair tied in a high ponytail.

The hanafuda earrings hanging beside his ears swayed gently in an imperceptible current of air, identical to the pair Tanjiro wore.

Kashu's gaze narrowed. A name long forgotten by the world rose to his lips.

"Yoriichi Tsugikuni?"

The man did not respond to the tentative call. As though immersed in his own world, his voice was filled with ancient loneliness and deep regret.

"I've actually... always wanted to find someone to talk to."

Kashu frowned slightly, swiftly analyzing the inconceivable situation before him.

A soul?

Impossible. This world had no Throne of Heroes.

How could the soul of someone from the Warring States era have remained until now?

So it was more likely some powerful obsession, imprinted upon the world—

An echo?

"I am a failure without any value."

Yoriichi Tsugikuni's voice was low as he spoke of the regret that had haunted his entire life.

"I failed to protect my beloved wife and child. I failed to fulfill my duty in life. I even... never understood my elder brother's heart..."

"And now, I have the shamelessness to place this burden upon another."

"I beg you, end Muzan Kibutsuji. Erase that darkness which should never have existed in this world."

The moment his words fell, the legendary swordsman deeply lowered his head.

The being who had once stood at the pinnacle of the world shattered apart, his body turning into specks of fluorescent light and fading away.

Kashu stared at the place where the figure had vanished, remaining silent for a moment before sighing softly.

He had heard something of Yoriichi Tsugikuni's life from Kagaya Ubuyashiki.

A tragically gifted swordsman, cursed by fate and condemned to lose things throughout his entire life.

"Even if you hadn't said it, I would have done it."

Kashu murmured to the empty white expanse, a sharp edge flashing in his eyes.

"I came here for exactly that, and besides—"

He clenched his fist, feeling the surging power within him and the ultimate realm of martial skill he had just mastered.

"The preparation phase is over. Muzan Kibutsuji, it's time to drag you out of the shadows!"