Isekai Adventure in the Dimensional Cube

Reiger's approach was indeed noticed by Nightmare.

Naturally, it induced fear in him.

As a Lower Rank One, the demon closest to the Upper Ranks, there were very few things that could instill fear in Nightmare.

To him, ordinary Ghost Hunters were no different from regular people.

Even against the Pillars, Nightmare was fearless, even eager to kill more to gain merit.

For demons, the constant ghost-hunting Demon Slayer Corps were a thorn in their side, and the master had long since issued orders to kill the Pillars, so Nightmare had never feared them. Otherwise, he would not have concocted a plan to merge with the Infinite Train and consume both the Pillars and two hundred passengers in one go.

As long as he could kill a Pillar, as long as he could consume a large number of humans, he could grow stronger and receive rewards from the master. Perhaps he would soon be able to challenge the Upper Ranks in a battle for position and become the newcomer in the ranks that hadn't changed in nearly a century.

Therefore, Nightmare had always approached the operation on the Infinite Train with a mindset akin to entertainment and enjoyment, for what he loved most was to see others suffer and despair.

The sight of the Pillars and those two hundred passengers struggling in agony before death must be interesting, right?

Every time Nightmare thought of this, he felt a surge of pleasure.

However, as it turned out, even non-human beings like Nightmare, even pleasure offenders like him, would feel fear when faced with incomprehensible events.

The way Reiger instantaneously disassembled the entire train and obliterated it with a punch was, to Nightmare, an absolutely incomprehensible event.

Especially since the train had already merged with Nightmare and become part of his body, Nightmare could clearly understand just how unreasonable the events of that moment were.

It felt as though his entire body was being forcibly disassembled by an unknown force, even the very essence of his being invaded, dominated, and decomposed. It was as absurd as watching his own cells being torn out one by one.

So, seeing Reiger approaching him, Nightmare exploded.

"Forced Slumber Sleep · Eye!"

Along with Nightmare's outburst, numerous flesh columns suddenly burst forth from the train's head, surging towards Reiger.

On the flesh columns, pairs of eyes fixated squarely on Reiger, emitting a strange ripple that projected onto Reiger through their gaze.

Demons naturally possess superhuman powers that frail humans cannot match.

Beyond their akin-to-immortal abilities and superhuman physical capabilities, some demons manifest special powers as well.

These abilities are akin to Demon Arts or superpowers, with some having bizarre effects, while others act like finishing moves, making them varied and multifaceted.

This is the Blood Demon Art, the unique abilities exclusive to demons.

Demons with Blood Demon Arts are generally stronger than those without, and some particularly powerful demons may even possess multiple Blood Demon Arts.

Nightmare's Blood Demon Art could force opponents into sleep and start dreaming, where he could control the people, events, and objects within those dreams, making those affected by his Blood Demon Art lost in their dreams without realizing it.

Once affected by Nightmare's Blood Demon Art, no matter who it is, their consciousness would be completely severed from their body, and they wouldn't be able to move unless they woke up from the dream.

The usual method to wake up from the dream is just one.

That is for the person trapped in the dream to have the resolve to commit suicide.

Only then can they voluntarily escape the dream and wake up.

Tanjirou woke up this way, then he burned the tickets of Rengoku Kyoujurou and the others, awakening them.

The two hundred passengers on the Infinite Train were also under the influence of Nightmare's Blood Demon Art, now still immersed in their dreams, unaware even as the train disintegrated and the carriages splintered; they continued to dream.

Now, Nightmare unleashed his Blood Demon Art at Reiger—Forced Slumber Sleep · Eye.

Unlike the previous distance spell cast through a medium of blood-soaked tickets, this was direct hypnosis through eye contact. Whether in effect or power, it was far stronger than the earlier distant hypnosis.

Unless one avoids direct eye contact, this move's success rate of hypnosis is one hundred percent, unpredictable and inescapable. Even the Upper Rank demons, if caught off guard by this move, would likely fall, right?

This monster had already met his gaze, so definitely he would...

...!?

Nightmare's eyes suddenly bulged wide.

Before him, Reiger locked eyes with the ones on the flesh columns but not only was he not hypnotized, he instead furrowed his brows.

"How disgusting."

Silver light flashed from the short sword in Reiger's hand as he swiftly unleashed several slashes.

"Splurt—splurt—splurt—"

Several flesh columns were dissected by the sword light, chopped into countless pieces, and scattered on the ground.

"Forced Slumber Sleep · Eye!"

Nightmare screamed again, causing more flesh columns to grow from the train head, their eyes all fixating on Reiger, releasing the power of hypnosis.

But that power couldn't even make Reiger hesitate in his steps.

Moving as if unaffected, Reiger stepped right up to Nightmare.

Nightmare dumbly watched this man, who seemed too diminutive compared to himself transformed into the train head.

After a while, Nightmare murmured.

"So this is my nightmare, then?"

These were the last words Nightmare left in this world.

"Buzz!"

The red wave violently smashed into the pitch-black train head.

This time, Reiger showed no mercy, exerting his maximum power, utilizing his disintegration magic to its limit, and vanished the entire train head into nothingness.

"Bang—bang bang bang—"

As the locomotive vanished, the walls of flesh that had once writhed within the halted train carriages all exploded.

Dismembered and then decomposed by Magic, such an end far exceeded the regenerative limits of this member of the Twelve Kizuki's lower ranks, preventing the demon from recovering.

The only surviving lower-rank demon of the Twelve Kizuki met a tragic exit here.

And Reiger?

He remained standing in place, looking at the large pit created by the disappearance of the locomotive, his eyes devoid of pity.

"Demons that eat humans deserve such an end," he said without warmth or coldness.

After dropping that indifferent remark, Reiger turned and left the area, leaving behind nothing but the hollow pit, its time of being filled unknown.

...

The man-eating incident on the Infinite Train had thus come to a close.

The guilty ghost had been slain, not a single one of the two hundred passengers injured, and none of the Demon Slayer Corps members had encountered mishap; such results could be called a complete victory.

Kyoujurou Rengoku was already in contact with the Demon Slayer Corps, arranging for them to come clean up and escort the two hundred passengers back, as well as send the disassembled Infinite Train back to the station.

However, it was unknown whether this Infinite Train, now left with only carriages and parts after its locomotive vanished, would ever be repaired and returned to service.

Of course, all that was a matter for the officials, not concerning Reiger, nor the Demon Slayer Corps.

The Demon Slayer Corps, acting as an unofficial civilian organization not recognized by the authorities, naturally had no need to concern themselves with official matters; they simply did not interfere with one another.

While waiting for the Demon Slayer Corps to arrive and handle the aftermath, Reiger found himself entangled by Kyoujurou Rengoku.

"Let's go, Box Boy!"

Kyoujurou Rengoku appeared in front of Reiger with his arms crossed, staring straight ahead and shouting loudly.

"Come back with me to the Demon Slayer Corps!"

Kyoujurou Rengoku, still shouting, was looking in the direction of the wilderness.

"...What are you looking at? I'm over here, okay?"

Reiger stood behind Kyoujurou Rengoku, watching the back that blocked his path and rolling his eyes.

"Let's go to the Demon Slayer Corps together!" Kyoujurou Rengoku continued to face the distance, shouting, "I will recommend you to our master! You can rest assured!"

"Rest assured about what?" Reiger pushed past Kyoujurou Rengoku, who was obstructing his way, and said, "The matter isn't even finished yet, and here you are, at ease."

Finally, Rengoku seemed to take Reiger's words to heart.

"Not finished yet?"

Kyoujurou Rengoku turned to look at Reiger.

Even the protagonist trio, who had been on their way, playfully jostling each other, had their attention drawn by Reiger's words.

"Wasn't the demon already defeated by Big Brother?"

Tanjirou wrestled his wooden box free from Zenitsu, who refused to let go, and, while strapping it to his back, he approached with surprise.

"Could there be another demon?"

Zenitsu, no longer vying for the wooden box with Tanjirou, had a look of suspicion and fear.

"Another demon? What is it this time? No matter if it's the locomotive or something else! Watch as I blast it to smithereens with my fists!"

Inosuke, his spirits uplifted, seemed electrified by Reiger's previous acts of valor; he tossed aside his beloved blade and clenched his fists, ready for action.

Then, they heard Reiger's words.

"It's an Upper Rank demon," Reiger said calmly. "An Upper Rank has arrived."

Upon hearing this, everyone's complexion stiffened at once.

Especially Kyoujurou Rengoku, whose face changed drastically, losing his usual cheerfulness.

The protagonist trio had an even more intense reaction.

"It's here!"

Tanjirou's nose twitched, then suddenly his expression changed drastically as he exclaimed.

"There's a sound, closing in fast!"

Zenitsu covered his ears, his face turning pale with terror.

"Over there!"

Inosuke forget about clinching his fists, hurriedly picked up his sword, and pointed vehemently in one direction.

There, a sound of tearing through the air grew swiftly louder, as a figure shot towards them like a cannonball.

"Boom!"

Seconds later, the figure landed with a deafening roar.

"Oh? Nightmare is really dead, huh?"

A young voice emerged from the dust.

"Lower Ranks are Lower Ranks after all, not up to par, incapable of handling real power."

Uttering these words, the figure emerged slowly from the dust.

In the air, an astonishing aura of fighting spirit suddenly spread out.