Reincarnated into a Multiverse, but High School DxD

Muzan was filled with resentment. He had only just awakened from a thousand-year slumber, and hunger had driven him to pick a lucky victim at random from this night market. After eating his fill, Muzan had planned to first learn about this era before deciding whether to go back to sleep or make a name for himself in this age.

But before he had even run very far, he was discovered by a group of demon exorcists from Tokyo's Five Great Houses.

Muzan fled in a panic, running with all his might without the slightest intention of fighting, no matter how much hatred filled his heart.

A dense barrage of talismans flew toward Muzan, but he was fast. The talismans that would explode upon touching his body were all evaded.

However, Muzan bore many wounds from the ambush, though his absurdly powerful healing ability had long since restored them to normal.

"Get out of my way!"

With his path blocked, Muzan let out a piercing roar as dozens of tentacles shot toward the demon exorcists.

He had already seen through it.

Every one of these demon exorcists was fighting with the intention of killing him.

If he showed even the slightest weakness, he might be torn apart the very next second.

Relying on his advantages in strength and speed, Muzan launched a fierce counterattack.

The lunging tentacles wrapped around a demon exorcist's body. Before he could react, they tore open his chest, and blood erupted like a fountain in an instant.

The blood that fell onto the tentacles was rapidly absorbed by Muzan, making him reveal an expression of pure delight.

Muzan had not expected that absorbing the flesh and blood of these demon exorcists would taste far sweeter than ordinary human flesh and blood! It could even increase his power!

Faced with such an overwhelming gap, the remaining demon exorcists realized they had encountered a formidable opponent and hurriedly retreated several steps.

But Muzan had clearly been driven into a corner.

At that moment, Muzan could not help recalling the days when he had thrown his weight around in a small city in the island nation.

But then, gods, demons, and other such beings had emerged one after another.

Even among humans, there were many who had awakened Sacred Gears.

All of that had left Muzan living in endless fear every day.

To calm himself and avoid being discovered by those beings, Muzan Kibutsuji had dug himself a grave in the wilderness and lain inside it, sleeping until now.

But who could have imagined it?

He had only just awakened, yet demon exorcists had already cornered him here.

"You're all going to die!"

Muzan Kibutsuji cursed viciously.

Then he charged forward like a cannonball.

He might not know magic or sorcery, but he possessed Blood Demon Arts, which were similar in nature.

Yet compared to those things, his powerful body was what had allowed Muzan to survive until today.

Muzan leaped into the air. The demon exorcists thought he was going in for close combat, but his right leg suddenly swelled with muscle and bulged with veins. The next instant, eight bone whips lashed out. Their force was so great that they tore through the air the moment they swung, setting off piercing sonic booms.

The impact on the ground was even more terrifying. A mere gust of wind cracked the earth along its path.

The demon exorcists failed to react in time and were instantly sent flying as if struck by a car. They crashed heavily into trees and the ground, with no telling how many bones throughout their bodies had broken. Their consciousness went dark, and their fates were unknown.

Of course, as the price, several explosive talismans were stuck onto Muzan's body, blasting him away.

Although his entire body was burning, ordinary flames could not kill someone with such tenacious vitality. Instead, they only made him look even more like a monster.

"I never intended to expose myself! But you forced my hand!"

Rage surged through Muzan. He was going to devour every last one of these demon exorcists alive!

However, just as Muzan was about to feast on the nearest female demon exorcist, a glint of cold light bloomed from the air before he could react.

Then—

His head rolled to the ground.

His extraordinary vitality did not allow him to die. Muzan stared at Ren in shock, having no idea where this guy had come from.

"His strength isn't much, but he really is as hard to kill as ever."

Ren muttered to himself.

Wasn't that true?

Although countless races in this world were stronger than Muzan, most of them would not be able to act as though nothing had happened after having their heads cut off.

Muzan's head, rolling on the ground, instantly flew into a rage when he heard that.

What did he mean, his strength wasn't much?!

He was the first Demon King!

Not only did he possess infinite regeneration, he also had the power to demolish buildings and shatter stones! Hadn't Ren seen what happened to those overconfident demon exorcists?!

Muzan's headless body attacked Ren. Dozens of tentacles and bone whips shot out from all over his body like cannonballs.

Their target was Ren's head.

Muzan was petty. He wanted to see whether Ren could recover just like him after his head was smashed apart!

Yet in the very next second, all those tentacles were severed in an instant, while agonizing pain continuously burned through his nerves.

His means of attack had been neutralized at once. Muzan froze for a second before finally reacting.

Then his face turned pale.

This was bad. He had run into an expert.

Muzan gritted his teeth. His body immediately swelled like a balloon before exploding apart, his humanoid form instantly turning into countless tiny pieces of flesh that scattered in every direction.

This was both a deceptive technique and a means of escape!

On one hand, ordinary people would instinctively think he had self-destructed after being defeated.

On the other hand, Muzan's powerful regenerative ability meant that even a single piece of flesh could restore him completely.

After self-destructing, his body could split into a total of eighteen hundred pieces of flesh. That meant even if his enemy knew they had to eliminate him completely, they would still need to kill him eighteen hundred times in a short period!

Then there was no then.

The instant Muzan self-destructed, Ren began accelerating at super speed. As a result, from Ren's perspective, Muzan's body had not even fully exploded. Some pieces were still clinging to his blood and bones.

Demon Slayer Day

Under those circumstances, Ren easily destroyed every last piece of Muzan Kibutsuji's flesh.

Even at the moment of death, Muzan had no idea how he had been killed.

A generation's Demon King had died a rather hasty death.

Though calling him a Demon King was not quite accurate.

In this world's power scale, Muzan was at most a mid-class Devil. He might even have been evenly matched against the Fallen Angel Raynare.

Looking at the entire world, he was nothing more than cannon fodder among cannon fodder.

Poor Demon King. He had even less screen time than the vampires Ren had killed.

When the demon exorcists woke up, what they saw was Muzan Kibutsuji being dismembered before their eyes.

Their expressions were somewhat stunned.

At first, they had thought an expert sent by their house had arrived, but seeing Ren's clothes, they realized that he was not from the Five Great Houses.

Nor did he carry the aura of a yokai.

Ren did not bother with those rookie demon exorcists for the moment.

After he killed Muzan, the system's reward notification sounded.

[You have successfully defeated Demon King Muzan Kibutsuji!]

[Reward calculation complete: Breath Concealment EX.]

"Breath Concealment? That's a great skill."

Ren smiled slightly.

As an idle drifter in society, this passive ability suited him perfectly.

With this thing, ambushes and pretending to be weak would both become much easier.

Just as Ren was musing over it, another mission notification appeared.

[You have killed all demons in this world! Calculating rewards...]

"I only killed one trash boss—oh, I see."

Ren immediately understood.

Muzan Kibutsuji was the sort who only cared about himself.

Because he feared death too much and worried that the demons he turned would betray him, he established a rule: once he died, every demon transformed by his blood would die as well.

He feared death, feared betrayal, yet could not stop himself from killing people. After killing them, he would hide away in terror for a while.

What a piece of trash.

[Reward calculation complete. Random reward skill: Dimensional Slash.]

[Dimensional Slash: A lightning-fast iaijutsu slash. After a brief charge, it unleashes a powerful slashing attack that tears through the air. Requires a bladed weapon to use.]

Dimensional Slash?

Vergil's skill from Devil May Cry?

After sensing the principles behind the skill in his mind, Ren confirmed that it came from Devil May Cry.

Ren had only ever watched others play that game, but even so, he had seen plenty of clips related to it.

Especially the protagonist's Dimensional Slash.

Never mind whether its damage was high or not—it was at least one of the coolest skills in the game.

Ren was very satisfied.

Being strong was temporary, but being cool was for life.

Having gained two useful skills, Ren was in an excellent mood.

This trip had not been for nothing.

As he pondered, Ren noticed movement nearby.

The rookie demon exorcists whom Muzan Kibutsuji had driven into a desperate situation earlier were supporting one another as they walked over.

"...Thank you for saving us. Without you, we would not only have struggled to escape death today, but that cunning evil demon would have once again brought disaster upon humanity!"

The speaker was a young girl with childish features. She looked about the same age as Ren.

Ren studied her face carefully but found that he had no impression of her at all. She was probably some minor supporting character who had only appeared briefly in the anime.

"...Are you from the Five Great Houses?"

Ren asked.

The girl's expression changed slightly at the question, as did those of several companions behind her.

There was no special reason for it. They were simply surprised that Ren had recognized where they came from at a glance.

"Yes. We are all disciples of the Himejima Family, the foremost of the Five Great Houses."

The girl answered softly.

As she said this, a trace of pride appeared on their faces.

"So it really is the Himejima Family..."

Ren had only said it casually, yet he had unexpectedly uncovered a faction with a considerable role in the original story.