Isekai Adventure in the Dimensional Cube

"This, this is...!?"

When that astonishing aura permeated the entire space, the trio of protagonists instinctively stepped back, their pupils trembling. They seemed to be greatly impacted.

Tanjirou, Zenitsu, and Inosuke, already possessing exceptionally acute senses, felt the aura, which even a normal person could clearly sense, amplified many times over in their keen perception, seriously affecting the three of them.

Under such circumstances, Tanjirou had unconsciously gripped his sword, sweat dripping from his head. Inosuke, like a wild beast provoked, had the hair all over his body standing on end while Zenitsu, clutching his head, squatted down on the spot, screaming with a pale face.

"You three, step back!"

Kyoujurou's face was grave as he stood in front of Tanjirou and his group, his body lowered, hand already resting on the hilt of his sword at his waist.

Only Reiger looked ahead with cold eyes.

There, the figure that slowly emerged from the dust revealed itself completely.

It was a young man with peachy-red short hair, golden eyes, body covered in deep blue tattoos, and blood-red fingernails.

The man was not tall, his outward appearance seemingly younger even than Kyoujurou, dressed in a purple-red short coat, with beads hanging from his ankles, barefoot, dressed like someone skilled in martial arts, clearly not someone to be provoked lightly.

If it were just that, it wouldn't have been much.

Most importantly, in the man's eyes, those golden eyes, letters were engraved.

The letters clearly visible in his eyes.

Left eye———"Three".

Right eye———"Upper Moon".

This was the mark of the Twelve Kizuki, the numbers in their eyes signifying their rank and identity.

The Upper Moon Kizuki have characters in both eyes.

The Lower Moon Kizuki have a character in one eye.

The demon before them was undoubtedly an Upper Moon.

"Upper Moon Three?"

Kyoujurou spoke gravely.

Upper Moon Three, the third-ranking existence among the Upper Moons, was now before them.

"I am Akaza."

The Upper Moon Kizuki identifying himself like this, his golden eyes engraved with letters staring fixedly at Reiger and Kyoujurou.

A smile full of fighting spirit slowly spread across his face.

"So that's it, isn't it?" Akaza seemed to understand something, his smile aggressive, he said, "To have not one but two such powerful auras here, no wonder a Lower Moon of that level died so cleanly. With your level, those kinds of existences could never beat you two, could they?"

Akaza's words were clearly directed at Reiger and Kyoujurou.

Clearly, this Upper Moon had seen through the fact that Reiger and Kyoujurou were the strongest ones here.

As for Tanjirou's group, they didn't even register in Akaza's eyes.

"Upper Moon Three, right?" Kyoujurou, still guarding in front of Tanjirou's trio, stared at Akaza and said, "Are you also the mastermind behind the Infinite Train?"

Kyoujurou thought that Akaza's appearance here was because he had planned the Infinite Train incident together with Nightmare, a Lower Moon One.

Unfortunately, this guess was wrong.

"Don't misunderstand, I'm not like those Lower Moons, I don't do such roundabout troublesome things," Akaza shook his head and said, "I just happened to be nearby and received the orders because something went wrong with the Lower Moon One."

"Orders?" Kyoujurou's heart stirred, he said, "Someone who can command an Upper Moon? Could it be...?"

Before Kyoujurou could finish his thought, Akaza already shifted the topic.

"What are your names?"

Akaza was actually interested in this aspect.

And his question was naturally directed towards Reiger and Kyoujurou.

"I am Kyoujurou Rengoku, the Flame Pillar of the Demon Slayer Corps."

Kyoujurou declared his name.

"As I thought, you are a Pillar."

Akaza was not surprised.

Rather, knowing that a Lower Moon of that level had been subjugated, anyone would first suspect whether the person who acted was a Pillar of the Demon Slayer Corps.

In the Demon Slayer Corps, only the Pillar level Swordsmen had the capability to slay the Lower Moon of the Twelve Kizuki, other ranks of Swordsmen could never threaten the Twelve Kizuki.

Even a Grade A Swordsman would be powerless against a Lower Moon.

Thus, to the Twelve Kizuki, the only ones really worthy of note were the Pillars, the opponents truly worthy of regard were likewise only the Pillars.

Akaza, having seen Kyoujurou, had already concluded he was a Pillar. Now, it was just a confirmation of his name.

"And you?" Akaza turned his gaze towards Reiger, his smile growing more intense, "Which Pillar are you?"

However, faced with Akaza's question, Reiger did not respond, merely continuing to look at him silently.

"Don't want to answer, huh?" Akaza seemed a bit regretful but was not angry, he said, "Alright, the mighty have their own temper, their own privileges. You indeed have the right to be proud."

With these words, Akaza suddenly looked up, releasing his unabashedly aggressive nature.

"But me, I am also a powerful being!"

As the words fell, Akaza violently stomped on the ground, shattering it.

"Spellcasting deployed!"

Akaza took up a martial artist's stance, planting his feet in a horse stance, and making an initial gesture, causing a twelve-sided snowflake array to appear beneath his feet.

"Destructive Kill· Needle!"

The snowflake array emitted a glow, making Akaza's golden eyes sparkle brightly.

"Danger!"

Rengoku Kyoujurou reacted intensely and, without thinking, stepped forward.

"Bang!"

At that instant, Akaza vanished.

He shattered the ground and the snowflake array beneath his feet, darting out like lightning. As the sound of an air explosion rang out, he brought a gust of wind and rushed in front of Reiger and his companions.

Everyone just saw a blur, as Akaza had vanished one second and reappeared in front of them the next, his face wearing an aggressive smile that now seemed much closer.

Tanjirou couldn't react.

Zenitsu couldn't react.

Inosuke likewise couldn't react.

Even though their senses were exceptionally sharp, in the face of absolute speed, their bodies couldn't keep up, let alone react.

Reiger's fingers twitched slightly.

It couldn't be helped, Akaza was indeed targeting him.

With an unafraid smile, the Upper Moon Three swung his fist at Reiger.

That strike was so fast that even the sonic boom couldn't keep up, only catching up as it was about to touch Reiger's face.

But Reiger stopped the action he was about to make.

Because—

"Flame Breathing·Second Form·Ascending Flame Sky!"

A flaming blade, erupting from below, slashed upwards toward Akaza's fist that carried the force of a sonic boom.

It seemed that before the fist could touch Reiger's face, the fiery blade would sever Akaza's arm first.

"Ha!"

Akaza, far from being alarmed, laughed wildly and twisted his arm, striking directly at the fiery blade swinging towards him without any intention of evading.

"Clang!"

The fist, carrying a sonic boom, collided with the fiery blade, ultimately causing a clear, metallic collision sound that flung both individuals back, creating distance between them.

"Flame Breathing·First Form·Fire!"

Flames wrapped around Rengoku Kyoujurou's entire body as he charged at Akaza with the ferocity of a rocket.

"Destructive Kill·Chaotic Style!"

Watching Rengoku Kyoujurou, who sped forward so quickly that his outline blurred and his entirety could hardly be discerned, Akaza's fighting spirit erupted. He didn't retreat but advanced instead, his hands striking out like machine guns.

"Boom—!"

In the midst of thunderous roaring, Rengoku Kyoujurou's charge was blocked by Akaza, whose punch, mimicking a machine gun, countered the slashing flame blade and seemed to engulf it in a torrential storm, threatening to completely obliterate it.

In an instant, the eyes of man and demon met, sparking fierce friction.

"Boom boom boom boom boom——!"

The next moment, the intense battle between the swordsman and the martial artist erupted without any warning.

Rengoku Kyoujurou, undeterred by his unsuccessful strike, swung wildly, his blade wrapped in fierce flames slashing towards Akaza, covering every conceivable angle yet subtly zoning in on Akaza's neck, making most of his slashes mere feints before targeting Akaza's vitals.

Akaza, undaunted, met Rengoku Kyoujurou's blade with his fists, barehanded, sending out rapid punches that repelled, knocked back, smashed open, and even blocked the blade, causing his hands to be sliced countless times, spilling copious amounts of blood.

In a battle involving such immense sacrifices, Akaza appeared utterly unconcerned. Instead, his fighting spirit and will to battle surged remarkably as he laughed, randomly swinging his devastating punches in a barrage toward Rengoku Kyoujurou.

As for the wounds on Akaza, given the terrifying regenerative ability of an Upper Moon demon, they healed in less than a second.

"Your attacks are useless, Kyoujurou!"

Akaza laughed heartily, suddenly throwing a punch at Rengoku Kyoujurou.

"Boom—!"

Another thunderous sound erupted as Akaza's forceful fist landed on Rengoku Kyoujurou's hastily raised blade, creating a shockwave and sending Rengoku Kyoujurou flying.

"Ugh...!"

Rengoku Kyoujurou couldn't stop himself from careening backward, his feet scraping the ground and kicking up dust and stones.

"Destructive Kill..."

Akaza immediately resumed his stance, preparing to launch his fist at Rengoku Kyoujurou, who was flying backward like a cannonball.

However, Akaza suddenly came to a stop.

Because, in front of him, another figure had appeared at some unknown time.

Akaza maintained his stance, his smile growing broader.

Reiger appeared before Akaza, his face calm but his eyes flickering with a trace of indifference.

The opponents exchanged.