The Reincarnate Became a Professor at the Academy

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Black Flame Demon King.

Known as the most dangerous Demon King, he was treated as a strategic weapon.

He now faced a being who threatened his existence.

Duke of Extermination.

A woman with bright blonde hair and blue eyes, wearing tight-fitting clothes.

A name he had heard often.

One of the most dangerous beings, along with the Heavenly Demon.

If one encountered them, even a Demon King must not engage alone or risked a pincer attack.

They were beings on par with the Demon Kings.

Daring to stand alone, they transcended the laws of the stars, favored by the gods.

Demon Kings.

They could never be equals with transcendents or gods.

Such was the nature of divine favor.

He had obtained a fragment of the Demon God.

Even that had increased his attributes, his strength growing to absurd levels in both quantity and density.

It allowed him to face five transcendents at once.

But when you met those two, avoid them.

The Black Flame King secretly mocked them.

It was ridiculous.

They couldn't suppress them and just ran away.

Cowardly bastards.

That was what he was thinking.

'It's dangerous.'

That thought occurred to him for the first time.

His life hung by a thread.

His flames, which burned all things…

…were being seared by the enemy's lightning.

Wasn't the compatibility bad?

No, it's similar to himself. His black flame that burned everything.

And the power of contagion.

Few could withstand the combination of those two powers.

However, that damn thing's power annihilated it.

Duke of Extermination.

A name given to her for obliterating enemies and allies alike.

-Khehehe!!

He felt it was dangerous.

But the Black Flame King had another desire emerge.

The desire for victory.

No, that's not it.

He wanted to test his flames against her lightning, to prove his black fire was stronger.

A base desire.

But the impure emotions of the Demon King itself nurture power.

The power thus nurtured.

Fwoosh!

It grew strong enough to instantly burn everything nearby.

Flame.

Black Flame.

Contagion.

The three powers merged, consuming his magic as fuel.

The black flame blazed fiercely.

Everything around was infected by the black flame. It was the Extermination Thunder possessed by the Duke of Extermination. The same applied to the body of the Black Flame Demon King.

Even the Demon King's body was infected and burned.

That was why the Black Flame Demon King was considered the most dangerous among all Demon Kings.

A fragment bestowed by the Demon God.

The Demon King became complete by devouring it.

Yet the black flame of the Black Flame Demon King burned even its own body.

The black flame spread contagiously in all directions.

Only then did the Duke of Extermination retreat backward.

'Tsk, it's become troublesome.'

It would've been nice if he just died quietly.

Of course, there's no such Demon King. The body of a Demon King was exceptionally tough.

Receiving a fragment of the Demon God, they even possessed immortality.

Demon Kings roamed alone.

Taking their demon followers with them.

Yet, the Demon Kings did not die at the boundary.

Even when gods and transcendents gathered.

Because their immortality and the body of the Demon King were unimaginably strong.

Unable to kill them, the transcendents banded together, leading to the current state.

The Boundary did not collapse.

There's a joke that the moment the Demon Kings united, the Boundary would fall.

That was how tough and undying the body of a Demon King was.

The Black Flame Demon King used his body to 'infect' and wield black flames.

It had started to grow stronger.

Crackle crackle crackle!!

-Kwahaha! Even with that blue lightning, you cannot pierce through!

The intensified black flames enveloped the surroundings.

Extermination Thunder.

Even that couldn't neutralize it.

"With just this?"

The Duke of Extermination stepped back.

Lightning Transformation.

It allowed her to momentarily reach speeds close to that of lightning.

'Striking and retreating isn't an issue.'

The Duke of Extermination thought calmly.

The boundary was vast.

It was tens of times larger than the Earth.

No, it might even be hundreds of times larger.

Originally, the boundary wasn't that large, but the gods combined their powers and used the remains of demons to expand it.

So there was no problem in striking and retreating.

No matter how strong that Demon King was at spreading contagion, buying time was…

There was a problem, though.

Some might say it was needless worry, but…

'It's embarrassing.'

Han Seojin was observing the battle.

The man she liked and loved was watching over her.

And yet, to show such a sight as if turning tail to the enemy.

It was a disgrace.

'It's all because of that damn woman.'

Heavenly Demon.

That damn woman ran away on her own.

She had temporarily cooperated to leave the Boundary, expending too much karma in the process.

Because of that, her strength weakened a bit.

As a result of accumulated desires, she managed to thin the wall a little.

But that was it.

As she thought up to that point, her senses warned of danger.

Sizzle.

Black flames lingered around. Not dangerous.

Just bothersome.

'Tsk, at this rate.'

She had to admit her head was filled with idle thoughts.

At the moment when the Duke of Extermination was about to escape from there.

Rumble!!

A colorless lightning swept the surroundings. The black flames, which even the Duke of Extermination's thunder couldn't eliminate, faltered.

In that situation, two beings flinched.

'I couldn't eliminate it, but…'

'Did my black flames falter?'

These were no ordinary black flames. The black flames obtained by burning the body of a Demon King were particularly dangerous.

'The realm…'

The being that appeared before them was weak.

But not on a level lower than himself.

Supreme Realm and Transcendent.

The power difference between those two realms was truly immense.

It was the most significant difference among all realms.

That was why Transcendents reigned invincible in the middle world.

To handle one Transcendent, more than ten beings of the Supreme Realm were needed.

However.

The Black Flame Demon King scrutinized Han Seojin.

'Supreme Realm.'

Merely, a Supreme Realm.

But he couldn't be underestimated.

The being existing behind him.

A giant about 3 meters tall, seemingly modeled after the human form.

As it gazed at him, he sensed it.

A feeling of unease.

He didn't know what it was.

He didn't know what kind of power it had.

But the feeling of unease said.

'Could I lose if I'm not careful?'

That's what it seemed to be saying.

Was it saying that it had the power to pierce through his body, now engulfed in black flames?

A monochrome lightning.

It was a bit dangerous.

If hit directly.

But could he, the Demon King, not avoid such an attack?

That was questionable.

While the Black Flame Demon King was contemplating.

The presence that had stopped all those black flames, Han Seojin, quietly appeared.

'That was close.'

More precisely, it almost became troublesome.

The Duke of Extermination wouldn't fall from just this.

But she might have gotten injured.

That fact didn't sit well with me.

'This foolish woman.'

I looked at the Duke of Extermination.

Even most men wouldn't do such a thing so casually.

Clearly, she was trying to put on a brave front because the person she liked was nearby.

'Since it's come to this.'

I held the Duke of Extermination in a princess carry.

"Eek!"

Eek? I almost shot a strange look at the Duke of Extermination but managed to hold back.

"Hmm…"

"Hmm?"

"This isn't so bad…"

I gave her a startled look.

Normally, if I were to carry her like a princess, she would blush and say, "I'm not a weak woman who can be carried by you!"

'Has time softened her?'

I was carrying her in the princess style to get her out quickly.

She was calmer than I expected.

No, rather, it seemed like she was burying her head in my chest and sniffing…

"You can hold me tighter."

"No, this is more than enough…"

"Hold me tighter."

"…Okay."

"And since I'm feeling a bit down, give me a kiss."

"...Later."

"Hmm… I understand. With that pig-like thing around, you must be feeling down too."

"Why would I feel down?"

"Just the sight of something ugly watching our beautiful moment is unpleasant…"

"…"

A slightly strange feeling arose.

The Black Flame Demon King resembled Zhu Bajie somewhat.

In other words, a bipedal pig.

But could it really make one feel down just by watching?

'I guess I wouldn't know since I've never had an ugly enemy…'

Still, it was certain that the Black Flame Demon King was in a foul mood.

'Though that's not my concern…'

It felt like the Black Flame Demon King might annoyingly follow me.

I looked at the Black Flame Demon King.

And then.

The demon's flesh inside my body buzzed in response.

-You.

The atmosphere around the Black Flame Demon King shifted.

It was different from just a moment ago.

Desire.

Greed.

No, it was different from those things.

It was as if he believed obtaining this would let him overcome his limits.

-Where did you get it? No, that's not what's important. What's important is that you have a piece of the Demon God.

The black flame rippled.

It began to change shape.

Some took the form of a dragon, and some took the form of a bird.

Things that changed into all sorts of shapes.

'It doesn't seem like only the shape has changed.'

If only the shape had changed, my senses wouldn't be sounding this alarm.

-You seem to be someone I haven't seen before. So, the piece of the Demon God you have and the doppelganger behind you. It was definitely the Manifestation of Thoughts.

But no.

Regardless, he began to mutter to himself.

-Manifestation of Thoughts.

The Black Flame Demon King clasped his hands together.

Things around began to change.

Domain, Infernal Hell.

At the edge of the boundary.

Standing guard there, Supplet let out a deep sigh.

'I didn't come here just to keep watch.'

Some say.

The boundary was a dangerous place.

That's true.

But it was also a land of opportunity.

A transcendent was one who defied the laws of the stars.

To further enhance that power, the only way was to grow stronger in the land of the boundary.

Training was an option, but it took too long.

The best method was to kill demons and absorb their power.

In doing so, one became slightly stronger.

That was how you elevated your realm.

It would take a while, but becoming a transcendent granted freedom from the limits of lifespan.

Thus, there was hope that it could be achieved one day.

However, the first task of a transcendent was to protect this place.

'Originally, that is.'

The woman who bore a grudge against the Iron-Blood Sword Clan should have guarded this place.

However, she was left out because she was considered a supporter who could provide buffs.

Supplet let out a deep sigh and then felt a strange sensation.

A sense of dissonance.

Everything around had come to a halt.

The entrance to the boundary.

Very few dare to enter this place without fear.

Nor do strong individuals come here.

'Who is coming?'

Tensing his entire body, he looked towards the entrance.

There was a woman.

An extraordinarily beautiful woman.

His heart, made of unwavering will, throbbed slightly.

"Hmm, seeing that I've found the gatekeeper, it seems I've come to the right place."

His heart throbbed.

Out of fear.

He might die here.

'Why that damn Heavenly Demon…'

The gatekeeper quietly held his breath.

Hoping she would pass by peacefully.