Isekai Adventure in the Dimensional Cube

"————"

Silence.

Deathly silence.

When the heads of the Upper Rank demons flew into the air in unison and fell to the ground, whether it was the blown-away Kochou Shinobu or Rengoku Kyoujurou, who was protecting Ubuyashiki Kagaya and hiding within the debris of the building, all were stunned by the shocking scene before them, their eyes wide open, losing all ability to react.

Their minds went blank.

Their hearts abruptly stopped.

They couldn't believe the scene before their eyes and fell into shock.

Especially Kochou Shinobu, seeing Reiger demonstrate his power for the first time, was now frozen in place, unable to produce any reaction other than that.

"Clack—clack clack—"

Within the mansion of the Ubuyashiki family, the sound of rubble and debris hitting the ground could still be heard from time to time.

The place had completely collapsed under the cataclysmic thunderstorm, with not a single intact area in sight.

Not only the Ubuyashiki mansion but also the surrounding area suffered the same fate, either blown into craters by the ferocious lightning or shattered into pieces by the hurricane winds. Add to that the ravages of destructive sonic booms, shockwaves, blood-colored air blades, and ribbons sharp as steel knives—there was definitely no unscathed scenery within hundreds of meters, let alone within a kilometer.

Even the forests had collapsed considerably, and the ground seemed like it had been shaved off a layer, presenting a desolate scene of overturned soil, akin to a wasteland under development.

And these scenes, reminiscent of the aftermath of a disaster, were ultimately shattered by the roaring cries that pierced the skies.

"It hurts...! It hurts so much... so much...!"

"Why does it hurt so much...!?"

"Impossible... It's impossible...!"

"Can't... regenerate...!"

The heads of the four demon clones—Urogi, Sekido, Aizetsu, and Karaku—fell to the ground and screamed out, rolling around desperately in apparent agony.

Their headless bodies also simultaneously fell, unable to split or regenerate, as if suppressed by some mysterious force. The severed necks of these bodies emitted flames, scorching them, and brought forth another torrent of excruciating screams.

"How could this... how could this be...!"

The head of Gyokko, which was said to be protected by scales harder than diamonds, was also chopped off and rolled on the ground, causing him both pain and disbelief.

"Three Upper Ranks... seven demons... all beheaded in an instant... with a single strike...!?"

Gyokko couldn't believe it, nor did he want to.

After all, the opponent was just a human.

After all, the Upper Ranks present were demons with survival abilities even stronger than Akaza's.

Yet such a group of demons, working together, were still beheaded in the blink of an eye...?

Not just Gyokko, Gyuutarou and Daki also screamed out.

"Stop kidding... Quit joking around...!"

The neurotic expression and the dead eyes of Gyuutarou had changed, becoming hysterical.

"My head was chopped off... not just mine... but my sister's too... in an instant...? By a human...? Impossible...!"

Gyuutarou, of course, understood the severity of the situation.

Both his and his sister's heads had been chopped off, which only meant one thing.

They were going to die.

"Brother! Brother! Think of something! Come on, think!"

Daki seemed to realize this, finally breaking down.

"I don't want to die! I don't wanna die!"

The desperate cries of his sister twisted Gyuutarou's face further.

But what could he possibly do?

Times had changed, and Reiger had not only evolved the Sun Breathing but also acquired his own Sun Wheel Blade and awakened new skills, completely different from when he fought Akaza.

The Hermit Sun Wheel Blade was fashioned from numerous purified essence of great ape crimson sand iron and great ape crimson ore, concentrating a large amount of their essence into raw material. The solar energy within had undergone a qualitative change, making its ability to kill demons far superior to ordinary Sun Wheel Blades. Therefore, any demon cut by Reiger's Hermit would suffer as if directly exposed to sunlight. Given enough time, they would surely rot and turn into ash, let alone if their heads were chopped off.

And the appearance of the skill "Pioneer of the Sun Wheel" gave Reiger an ability to special attack evil entities and suppress their powers.

This resulted in not only the suppression of the demons' regenerative abilities but also an enormous amplification of the damage they received.

Together with the sword form that Reiger used—"Corona of the Dragon: Head Dance"—the eleventh form of Sun Breathing, not only did it cause intense pain as if the wound were scorched by flame, but it also temporarily suppressed the demons' ability to regenerate. All these factors together meant that the demons whose heads were chopped off by Reiger were beyond any hope of standing up again.

This was an attack executed in the span of one second!

From the moment that fiery dragon rose from the disaster, the fates of these demons had been sealed!

Ubuyashiki Kagaya was the first person to recognize this fact.

"Cough cough...!"

The rush of emotions made Ubuyashiki Kagaya cough violently, even coughing up blood.

"My lord!"

Rengoku Kyoujurou finally reacted, hurriedly supporting Ubuyashiki Kagaya.

However, Ubuyashiki Kagaya paid no heed to his own body and instead grasped Rengoku Kyoujurou's hand tightly in return.

"Did you see that? Did you see that, Kyoujurou!"

Ubuyashiki Kagaya's voice trembled.

"In an instant... just a single instant... the Upper Ranks, who weren't even matched for the Hashira, had their heads chopped off... three of them...!"

Ubuyashiki Kagaya's voice became so agitated that it turned incoherent.

Rengoku Kyoujurou certainly saw it.

It was precisely because he saw it that he understood why Ubuyashiki Kagaya was so agitated.

The powerful Upper Moon, one of the strongest demons who could single-handedly crush even the Hashira, the human nightmare that had not been replaced in a hundred years, the nightmare of the Demon Slayer Corps, was now, before Reiger, unable to move past a single move.

And the way they looked, it seemed they couldn't regenerate or recover, which was too unrealistic, so unrealistic that even Rengoku Kyoujurou, who had witnessed a similar scene during the Infinite Train incident, could hardly believe it.

And if Rengoku Kyoujurou felt this way, there was no need to mention Kochou Shinobu.

"In a flash..."

Kochou Shinobu collapsed beside the wall debris, watching the figure whose body's firelight and high heat gradually dissipated, a glimmer of astonishment appearing in her eyes.

In the aftermath that transformed the Ubuyashiki estate, suddenly, there was only the hysterical roars of rage and excruciating screams of the Upper Moons, informing others that this was no dream.

Not long after, the bodies and heads of these demons began to turn into ash, gradually dissipating.

"Brother... Brother..."

Daki, the weakest in power, was the first to disappear, vanishing amidst her wails.

"…!"

Gyuutarou seemed to cry out something as he watched this scene, petrified only after his sister had completely vanished, stopping his howls of anguish, his screams of pain, as if he lost the most precious thing in life, he stared blankly in the direction where his sister disappeared, and after a while, he closed his eyes, letting himself turn to ash.

"Ah... My body is vanishing... I'm dying... Why...? Why so soon...?"

Gyokko was still unwilling to accept this reality.

Perhaps it was due to Reiger's special attack ability, or perhaps it was because the energy of the sun contained within Hermit was indeed intense, the Upper Moons who should not have been eliminated so quickly, who could have lasted much longer, seemed to be dying off at an astonishing rate.

"I still have so many artworks to complete... How could I die here... How could I...!?"

Gyokko muttered to himself for a while, then suddenly thought of something and cast a crazed look in the direction of Ubuyashiki Kagaya.

"At least... At least take the people of the Ubuyashiki family with me...!"

This was the last bit of resistance Gyokko furiously conjured.

The tasks Kibutsuji Muzan had assigned were to investigate Tsukiguni Yoriichi and kill him, and to bring back the heads of the Ubuyashiki family.

Gyokko dared not even think about facing Reiger.

But when it came to Ubuyashiki Kagaya, Gyokko felt, he must drag him down with him before his death, no matter what.

However, just as Gyokko began to entertain such a thought, he discovered that the monster had appeared before him.

Reiger, wielding a black blade, was somehow already in front of Gyokko, looking down at him from above. After a moment, he lowered his head and whispered a sentence in Gyokko's ear.

That sentence caused Gyokko's eyes to widen dramatically in fear as he looked into Reiger's eyes.

Before his death, this Upper Moon Five seemed to foresee something.

He foresaw a full-scale battle with that supreme king—the same scene playing out before the monster before him.

With such a premonition, such terror, Gyokko finally turned to ashes and vanished completely.

As for the "Happy, Angry, Sorrowful, Joyful" four demons, they had already vanished, disappearing even faster than Gyokko, as if intentionally fleeing, racing out of this hell.

And with that, all of the Upper Moons who had attacked the Demon Slayer Corps Headquarters were gone.

Reiger indeed had done it.

He, just as he declared at the beginning, had dealt with the demons.

"Are they all dead?"

Rengoku Kyoujurou murmured subconsciously.

Reiger heard him and shook his head.

"No, it seems one has escaped."

Reiger's words stunned everyone.

...

Nearby the Demon Slayer Corps Headquarters, by the town.

In a dark corner, a demon the size of a palm suddenly appeared here.

With horned forehead and a Rakshasa-like face, it was Hanagengu.

This was the true form of Hanagengu, the real person of Upper Moon Four.

Rengoku Kyoujurou would never have guessed that although Hanagengu appeared to have split into four, those four copies were just that—copies. Hanagengu's true body had always hidden in the shadows like this, which was why the clone demon could regenerate and split no matter how many times its head was cut off.

Only by beheading the true body would Upper Moon Four Hanagengu be vanquished.

But Hanagengu's true body had always been hidden in the dark, never showing itself on the battlefield.

He should feel fortunate.

If he had been present, even if he had shrunk so small and hid in a corner, Reiger would have been able to find him using Transparent World.

When the "Happy, Angry, Sorrowful, Joyful" four demons appeared, Reiger had already used Transparent World to search for Hanagengu's true body, but unfortunately, he did not find it.

Thus, Hanagengu had narrowly escaped fate.

But he could find no joy in his escape.

"Terrifying... Too terrifying..."

Hanagengu trembled with fear in this corner, overwhelmed by terror.

"I must escape...!"

Recalling the human swordsman who seemed even more monstrous than a demon, Hanagengu became filled with fear and began to flee in panic.