Their sword tips faced each other, and the air seemed to freeze.
Everyone's eyes turned toward them.
Sanemi tightened his grip around the broken hilt of his sword. Gyomei poured the last of his strength into his massive axe.
Shinobu Kocho struggled, trying to stand.
All of them were watching, waiting for the instant Shinichi clashed with that figure who seemed almost like a god.
And yet, the earth-shaking, terrifying battle they had imagined never happened.
Shinichi moved first.
He did not use any Forms of Forest Breathing.
He did not even activate a Breathing Style. He simply gripped his Nichirin Sword, stepped forward, and swung.
His movement was clean and decisive, without the slightest trace of flourish.
The sharp blade went straight for Yoriichi Tsugikuni's throat.
Yoriichi tilted his head slightly.
The blade skimmed past his neck by a hair's breadth. The old, simple-looking Nichirin Sword in his hand turned lightly, and the back of his blade struck Shinichi's sword with a crisp metallic ring.
Then, taking advantage of the momentum, he thrust forward.
Clang!
Shinichi drew his blade back in time to defend. Their edges collided, sparks scattering outward.
Shinichi did not stop.
His blade turned, and he continued with a horizontal slash toward Yoriichi's ribs.
Yoriichi retreated half a step, flipped his wrist, pressed his blade downward, and blocked the strike with perfect precision.
Another clang rang out, sparks bursting from the point where their blades met.
Chop, slash, thrust, upward cut, sweep, rising strike, draw cut.
The two of them exchanged blows amid the ruins of the Infinity Castle, their blades clashing again and again.
The crisp sounds of metal striking metal poured out like a rainstorm, endless and unbroken.
There were no dazzling colors from Breathing Styles.
No overwhelming sea of sword light.
What remained was only the purest, simplest contest of swordsmanship.
For a moment, their exchange seemed less like a battle and more like a traditional duel between ancient swordsmen.
Each move and each technique could be seen clearly.
Sanemi froze.
That monster had shattered his Wind Breathing with a single slash.
That godlike demon had sent Gyomei flying with one casual strike.
So why was he using this most basic kind of swordsmanship to trade blows with Shinichi?
On the other side, Gyomei could not see, but he could hear.
The steady ringing of blades colliding came again and again, its rhythm stable, neither hurried nor slow.
It did not sound like a fight to the death. Instead, it sounded more like some kind of… sparring match.
Or perhaps instruction?
Yes. Instruction.
An absurd thought rose in Gyomei's heart.
That legendary strongest swordsman… was he teaching Shinichi?
Compared to his companions' confusion, Shinichi, who was actually crossing swords with Yoriichi, felt it far more clearly.
Every time his Nichirin Sword slashed out, Yoriichi was able to predict its path in advance.
He was not crushing Shinichi with superhuman speed or power.
Instead, he used the most precise angles and the most appropriate amount of force to neutralize every single attack.
The feeling was like facing a mirror.
Every move Shinichi made was perfectly reflected back at him.
Not fast enough. Not accurate enough. Not stable enough.
Every flaw in every swing Shinichi made was laid completely bare beneath Yoriichi's blade.
And yet, strangely, Yoriichi never pressed his advantage.
He only blocked, deflected, and guided.
Gradually, as their blades continued to collide and their bodies shifted and dodged, Shinichi's breathing began to change.
It was not intentional, but a natural instinct.
During the constant collisions of their blades, the rhythm of his breathing slowly quickened, gradually synchronizing with Yoriichi's breathing.
He could even feel the wind in the air, the broken stones beneath his feet, the faint presences of his companions in the distance, and the tiny changes in the muscles of Yoriichi's arm as he swung his blade.
Everything became incomparably clear.
'Wait.'
'This familiar feeling…'
Shinichi had experienced something like it before when using Breathing of Life.
Having viewed Akaza's memories, Shinichi knew that this seemed to be the supreme realm martial artists had pursued for hundreds and thousands of years—
The Transparent World.
As though sensing Shinichi's hesitation, a faint light flashed in Yoriichi's eyes.
He increased the speed of his blade.
But it was not the kind of speed that became invisible.
Instead, he used a more aggressive rhythm to guide Shinichi's breathing, forcing it to accelerate further.
Ping!
Crack!
Clang!
Bang!
The sounds of their blades colliding grew denser and denser. The sparks became brighter and brighter.
The two figures moved rapidly through the ruins, and the surrounding scenery began to blur.
Only each other's blades remained perfectly clear.
And at a certain instant, Shinichi felt his breathing finally synchronize completely with Yoriichi's.
In that moment, the entire world seemed to change.
He could see the faint traces of air flowing.
He could sense every speck of dust as it drifted down.
He could even predict the angle of Yoriichi's next slash.
Was this the world Yoriichi Tsugikuni saw?
This was the Transparent World!
Shinichi understood.
He had never truly stepped into that realm before.
All of his previous perception had merely been a shallow imitation brought about by Breath of Life.
It was borrowed light.
But now, Yoriichi had personally led him into this supreme realm.
"You finally see it."
Yoriichi's voice rang out amid the clashing blades. It was still calm, but there was a trace of relief in it.
Shinichi did not answer.
His sword became faster.
It was not that his raw speed had increased.
Rather, every slash had become more precise and more decisive.
There were no longer any unnecessary movements, and no more hesitation.
A blue-green light flowed across the blade.
It was not something he deliberately forced out.
It was an instinctive resonance between his breathing and his sword.
Clang, clang, clang!
The sound of their blades colliding merged into one continuous stream, like an ancient battle song.
...
At the same time, on the other side of the Infinity Castle.
Inside the secret room of the temporary command post, the air was almost frozen.
The young Master, Kiriya Ubuyashiki, sat on a cushion.
Spread out before him were more than a dozen sheets of paper covered in lines.
Every sheet was a structural map of the Infinity Castle, drawn by Yushiro using his Blood Demon Art.
His eyes were bloodshot, but they remained bright and sharp.
Countless pieces of information gathered in his mind, where they were analyzed and inferred.
Every command he issued was transmitted with perfect accuracy to the various battlefields through the Kasugai Crows.
Members of the Kakushi came and went, constantly gathering and reporting the information brought back by the Kasugai Crows so that the Master could make decisions.
It seemed no one realized that their Master was still a child under ten years old.
"The members in the southeast have been surrounded. We need to send support immediately. Please have Kinoto-ranked swordsman Mr. Konaka lead a team there. Also, on the western side…"
Kiriya's voice was young, but steady.
His fingers moved swiftly across the maps, calmly and orderly dispatching Demon Slayer Corps members through the chaotic Infinity Castle.
Suddenly, Kiriya Ubuyashiki stopped moving.
His brows furrowed slightly, and his gaze fell on a newly delivered map in front of him.
"Wait. The data here is wrong. Yushiro-san, please reconfirm Area Two's—"
Before he could finish speaking, Tengen Uzui, who had been silently guarding nearby with his eyes closed while recovering his stamina, suddenly snapped his eyes open.
He had not heard any sound.
He had not sensed any presence.
But before his brain could even issue a warning, his ninja instincts had already sounded the alarm.
Something was coming.
Fast.
Unbelievably fast.
"Master!"
His hand instinctively pressed onto the hilt of his blade, and his body sprang from its guarding position like a released coil.
The sound of his chain-linked dual Nichirin blades leaving their sheaths was almost simultaneous with his movement.
A silver-white flash of steel cut through the secret room.
Boom!
The ceiling shattered faster than Tengen Uzui's blade could move.
A figure descended like a meteor, wrapped in a scarlet mist, instantly enveloping Tengen, who had just risen to his feet.