I Became the Final Boss’s Limited-time Teacher

Chapter 14



Hmmm… Once upon a time, there was a martial artist who had reached a certain level of skill, and even when discussing martial arts, there was a picture painted in their mind of the battlefield.

But now, this duel wasn’t just talk — it was layered with mutual respect for each other’s martial arts knowledge and inner power allocation.

They clashed, seeing, hearing, realizing, and training together. It was a crystallization formed from effort and determination.

I closed my eyes. Suddenly, the energy of Biyeol felt even more vivid.

In a dark space where I couldn’t see an inch ahead, a girl with black hair stared at me with wide eyes.

‘Using the Heavenly Demon’s Imperial Walk to close the distance and aiming for a weakness like my eyes with the Heavenly Demon Blood Slaughter Slash? She’s not like the girl who usually pouts at me.’

She was like a perfectly honed sword. The murderous intent enveloped me, and I vividly recalled the moment the tip of that blade aimed at my throat.

“Just three seconds left, Master.”

Biyeol’s heart murmured slowly and heavily. Perhaps she thought I succeeded in defense by a hair’s breadth; there was a hint of laughter in her voice.

Biyeol had fallen into a state of extreme focus and was on the verge of reaching an ultimate state, and I was similarly close to that peak.

‘Not a wrong judgment. But…’

Ultimately, what mattered in this duel was how to fill the gaps and how well one could comprehend the opponent’s moves.

New realizations or breaking conventions only applied at levels above the threshold.

To surpass the limits of the ultra-peak, it required bloody effort and solid fundamentals. Everything must be prepared.

“I will use the Heavenly Demon Art’s third move, Heavenly Demon Soul Attack, to break your mind. So, how will you respond?”

A move as poisonous as the ultimate technique that creates illusions using demonic energy, akin to closing in on a Go board, preventing me from escape.

This move thrown by Biyeol’s heart was exceedingly meticulous and sharp.

First, blocking my escape using the Heavenly Demon’s Imperial Walk and forcing me to focus on defense with the Heavenly Demon Blood Slaughter Slash, she was targeting the moment a mental gap appeared.

However, I resolved to turn the tide.

“I will evade behind your back using the Sichuan Tang Clan’s Silent Dragon Blood Step, stepping on your poison.”

With the precision of placing a pure white Go stone, I had moved one step ahead of Biyeol.

In a time span shorter than a heartbeat, I had defended against all the attacks Biyeol’s heart had mentioned.

Thinking I had countered all the techniques of the Heavenly Demon that were described as the strongest in my original novel, King of Diamond Fist, a fiery sensation surged inside me.

How long has it been since I felt this way?

A feeling that can be called excitement or fighting spirit. It was the opposite of the emotions I usually felt while living a life on borrowed time.

“That’s impossible! How can a Heretical Master use righteous martial arts?!”

Biyeol’s heart shouted in a voice mixed with surprise and anger. But I chuckled lightly and replied.

“Why not? In this duel, form and limits don’t exist. Beyond the boundaries of righteous and heretical, we are discussing the essence of martial arts.”

I tossed a line that Biyeol’s heart didn’t expect. The essence of this duel wasn’t merely a technical exchange of martial arts; it was about discussing the beyond.

Originally, when a duel involves words, it is a type of battle that doesn’t adhere to form or limits.

Biyeol, who was learning Heavenly Demon Arts, could use the righteous martial arts of the Wudang Sect, and I, with the extreme energy physique, could use martial arts with extreme qualities.

Heretical factions could use righteous methods, and low-grade martial arts could become first-rate depending on the context.

“But you must use only the moves you can certainly perform…!”

Biyeol’s heart scolded me, perhaps not having predicted this. If I only used the Ice Crystal Divine Art, I could never win against her.

“In a vast martial world, it’s reasonable to gauge what martial arts my opponent can use.”

This was Biyeol’s first real duel. It’s likely she thought that just as in actual combat, one could only use techniques that they could exhaust in inner power.

“I am the Ice Dragon. In the righteous conflict, I am a well-known Heretical Master who claims to be a member of the Heavenly Demon Divine Sect and even saved children.”

“…….”

“Did you think I became strong without any effort? Did you think I was just a simple-minded fool, believing the heavens gifted me a physique and that the whole world was in my palm?”

I added with a smile. This duel wasn’t merely a technical clash to me, it was an exploration of the essence of martial arts and reading the heart of the opponent.

“I will grasp the fragments of Ice Dragon’s art and tear them apart to create a sharp sword to target your central acupoint. I will pierce with the Three Talented Sword Method.”

“Isn’t that just a low-grade martial art?”

“But in this world, there are those who have transcended such low-grade arts into first-rate techniques. Those who are called the best in the world with simple moves of cutting sideways, cutting vertically, and thrusting.”

That was the swordsman described in my novel King of Diamond Fist. I wanted to meet the Infinite Sword Master of Namgung Clan and the Poison Dragon of Sichuan Tang Clan, as well as the Heavenly Demon Clan Leader, hoping to gain their teachings.

I sought to strengthen myself, without discrimination against righteous or heretical, and even in the outer martial world, if there was a way to be stronger, I pursued it.

“If you don’t block, you will lose the use of your right arm. Would you still be fine with that?”

Even with the ominous energy so strong that I couldn’t learn many martial arts, that didn’t mean I couldn’t reach the fullness of martial arts.

“Aha! Girl, I’ve realized! This is the breaking of formality! Master is still teaching me!”

“That’s wrong…”

In that moment, I dived deeper into her heart. I pictured Biyeol, not in her usual white robe, but wearing a black robe.

In this imagined state, she was no longer just a simple girl. She was now prepared to face me equally as a Heavenly Demon.

“Then I will also use a sword style! I will challenge you with the Namgung Clan’s Lightning Thirteen Blade Thunder!”

The moment Biyeol’s heart drew her sword in imagination, I clashed back against her momentum.

“I will block your sword strike with the Fire Dragon Sword of the Point-ness Faction.”

Clang—!

The sound of metal clashing echoed, and our swords danced like sparks flying off, hurtling towards each other. Biyeol’s heart cried out with vigor.

“Are you surprised? I pushed you to take a step back!”

As she said, I had unintentionally stepped back. A question began to bubble inside me.

‘…How?’

I couldn’t hide my surprise watching Biyeol in disbelief. How did she know the sword techniques famous for heaviness from the Namgung Clan?

“I wanted to slice off your right arm, but I’ll settle for this.”

The sword path I couldn’t fully block grazed my right shoulder.

“I shall immediately utilize the Jegal Clan’s Iron String Sword Method as a foundation to use the Moyong Clan’s Flashing Cloud Sword to aim for your ribs!”

The Biyeol I knew didn’t know how to use such techniques. But now, she was perfectly commanding the martial arts of the Five Great Clans.

‘The sword of Namgung Clan contains the intricacy of heaviness; the Moyong Clan’s sword embodies the swiftness. How did she know and employ that?’

Biyeol’s heart was no longer the Biyeol I knew. She had transformed into a Heavenly Demon like the one depicted in the novel.

A looming force that could grind down all life under heaven, one that no martial artist could match.

“Then I will use the foundations of the Gu Pah’s martial arts.”

Utilizing the same arts of the Five Great Clans could lead to being overpowered. Instead, I had to give it a twist and flip the board.

“I will use the Volcano Sect’s sword imbued with change to deflect your attack and use the Qing Cheng Sect’s Clear Wind Leg to strike your abdomen and widen the distance.”

“I will widen the distance using the Heavenly Play Divine Step.”

A new sensation arose. Our duel had transformed into an endless psychological war, as we both utilized martial arts we had never used before, trying to overturn each other’s board.

To seize victory in this battle, I needed to accurately grasp her heart.

“…Biyeol.”

“Yes, Master. Command me.”

I had to confirm this part. The demon that hid within her heart might just be Biyeol’s original future that I couldn’t erase.

“Are you really not Biyeol, yet it’s true you’re a heart demon?”

“Indeed, you perceive correctly. How astonishing.”

The fate of the Heavenly Demon Star was such that it couldn’t escape its path of slaughter.

“Honestly, I do not know well either. One day I just woke up, and both the feelings for you and the fate of slaughter became intertwined.”

“What a wondrous thing, how could that be possible?”

While talking with Biyeol’s heart, I felt she had more in common with her than I expected.

Just as there is shadow where there is light, her hidden true feelings couldn’t fall.

“That is the love that the girl learned from you. A powerful emotion that can encompass all things.”

In the original King of Diamond Fist, the protagonist, Kim Hyul, completely eradicated his heart demon and achieved a new realm, but…

“If by burning this body I can relay a good girl’s heart to you, this vile specter can disappear anytime.”

“Heart demon, how could you think of dividing good and bad in your heart?”

“…Yes?”

I felt that I shouldn’t just mindlessly erase her heart demon. I clenched my teeth and reproached her.

“The weakness in people is precious. That emotion is the reason one can feel compassion for others.”

This was a flow not present in the original novel. Since she had understood human emotions and wandered through them, the heart demon had come forth.

“Master…”

“…So you call me Master as well. What I’ve done is merely outstretching my hand so you can rise once you’ve fallen.”

Even Biyeol’s heart, who bore the burden of the Heavenly Demon Star and had to commit murder, called me Master, suppressing that desire as much as possible, and it felt oddly familiar.

“Heart demon, do you remember what I said when I first met you?”

The girl with black hair, bound by shackles, huddled on the cold ground.

When I first saw Biyeol at the Heavenly Demon Divine Sect, she had those hollow eyes just as she did now.

I had received countless wounds while protecting her.

“You said, ‘Seoljung Songbaek’.”

Looking down at the body now marred with ugly scars, the heart demon before me wore a sad expression.

“Yes, do you now understand what that means?”

“Pine trees and cedar trees do not lose their color even in the snow; it refers to a person of steadfast integrity, like you, Master…”

I shook my head at that answer. Inside the imagined space we were in began to show the image of the Heavenly Demon Divine Sect I had eradicated.

I could finally set foot in Biyeol’s imaginary world.

“No. Biyeol. When I mentioned Seoljung Songbaek, I meant you.”

“…? I don’t understand what you mean.”

“I knew you tried not to lose your humanity, even in such situations.”

As I carefully observed that imaginary world, I saw that in front of the church where rain was pouring heavily, the black-haired girl I originally knew lay collapsed.

“You could have given up and fled. Accepting the fate of the Heavenly Demon Star, you could have killed people and survived.”

The sound of crunching snow echoed under my feet, and I brushed the snowflakes from Biyeol’s head with my hand.

“But you did not. You never lost hope in the darkness and tried to save everyone.”

“Master…? What are you doing here…?”

The original Biyeol, who knew me, slowly opened her eyes and regained her senses, and I smiled gently at that sight.

“How could a flower blooming in the snow be easy; don’t you think life that endures that extreme cold is beautiful?”

And then, I created a sword from ice and handed it to Biyeol.

“You are Seoljung Songbaek. No matter what hardships come, you represent unchanging vigor. So, do what you believe is right.”

Winning the battle against the heart demon was, in the end, a task she had to do for herself.

“This Master will be here to help you along the way.”



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