Prologue: The Last Lesson
The dimly lit palace was filled with streams of lava that cast a bright, hellish glow in scattered places. It truly resembled a palace shaped from the depths of the underworld itself. Pillars etched with intricate patterns rose from the dark marble floor. Yet the scene made it clear this was no ordinary royal hall—five figures slowly picked their way forward, stepping past the gruesome corpses of demons that lay fallen everywhere.
I sat upon the cushioned throne, waiting for them to approach.
The five men and women who now stood before me were all people I knew well—my former comrades. Their expressions were heavy, as though they were being forced to carry out something they desperately wished to avoid. Understanding their hearts, I spoke in the brightest voice I could manage.
“Have you finally made up your minds?”
“Master…”
The beautiful woman with long blue hair was the Hero. She was the one destined to defeat me and prevent the world’s destruction. I closed my eyes and spoke her name.
“Scarlet…”
The time I had spent with the Hero’s party had been joyful. No—happy. With them, I could forget I was the Demon King and simply exist as a human. I could briefly escape the agony that gnawed at my soul after being cast into this unfamiliar world and trapped inside an endless regression loop. That was why I had been truly, deeply happy.
Perhaps I had stayed with them too long. Their hesitation was plain to see.
“You still haven’t decided.”
“Not yet… I still don’t know what I should do…”
Leaving the flustered Scarlet behind, the elf stepped forward.
“Kai-rak… Let’s find another way. There must be… there has to be another way.”
The beautiful elf with brilliant golden hair. His eyes trembled faintly. I smiled at the sorrowful-looking elf.
“Eden, weren’t you the one who hated humans? You’ve changed.”
It was my attempt at a joke, but he only made a bitter face and could not speak.
“I may hate humans, but I do not hate those who are righteous.”
“The God will surely help us! Please don’t give up, Kai!”
I shook my head at the words of the beautiful Saintess with grey hair and red eyes.
“Do you know how many years I have lived? How many attempts I have made? You could not possibly understand.”
I felt sorry for Cecilia, but I had once even sealed the god in my attempt to escape this cursed fate, and still my destiny had not changed. I kept that part to myself, afraid it would shake her faith.
While she hesitated, a sturdy young man in splendid plate armor stepped forward.
“Hyung! Don’t resign yourself like this! You’re the one who told me never to give up!”
The boy who had once pretended to be a knight and wandered between tournaments had become a true knight. Now in his late teens, Patrick had a brilliant future ahead of him—one I would never have. And I envied him for it.
“Hehe, I’m not giving up, Patrick. This is fate. Do you understand how many sacrifices would follow if we tried to change it?”
He probably understood my meaning. The mere fact that I still lived meant the end of the world. Seeing him bite his lip hard, I felt a quiet satisfaction. It warmed my heart to witness how much the Patrick I had once taught had grown.
“To think you were truly the Demon King…”
The short, red-haired young mage stepped forward.
“Edward, did you believe I wasn’t the Demon King?”
He shook his head.
“Yeah. I wanted to believe you were just talking nonsense. I never imagined the world could be this cruel…”
Tiny teardrops glistened in Edward’s golden eyes. As the youngest member of the party, he must have found the situation almost impossible to accept.
“Even so, I want to protect this world. And I hold no resentment toward any of you.”
I did not resent my dear friends. If anything, I felt gratitude and sorrow. Had our positions been reversed, I would have been devastated. But sadness does not protect the world. It is cruel, yet a lion must eat meat and a deer must graze on grass. Cold as it is, if a lion feels pity for the deer, the lion will perish. That is the law of nature.
In the same way, the Demon King had to die by the Hero’s hand. That was the only path to saving humanity and the world.
Who knows… perhaps when I die, I might return to my original world…
I could not know what would unfold after my death. At least this place would be safe.
“Hehe, I think that’s enough for greetings. Scarlet… I will give you one final lesson.”
“Master… can’t we… just not do this? You don’t hate humans, right? On the contrary…”
I cut off her faltering words with firm resolve.
“Scarlet. I told you that a Hero must be decisive, did I not? Are you planning to betray the people who believe in you, follow you—yes, the entire human race that has placed all its hopes on you?”
I understood the tender heart behind her weak words. But now was not the time for Scarlet to be fragile. If she did not kill me, everyone would die. And it would happen regardless of my own will.
Until now I had been allowed to remain a gentle teacher. But because of that gentle teacher, I did not want to shake the heart of the disciple who would now have to fight me with her life on the line. I truly wished for Scarlet to kill me and survive. For her to live, there was no path except to take my life.
“In any moment, your sword must not waver. Especially not before the Demon King.”
I continued, staring directly into her eyes.
“But…”
“Never forget that showing mercy to an enemy means your own death—and your death would mean the death of all humanity.”
I reminded Scarlet once more of the burden a Hero must carry.
“The weight of a Hero is equal to the weight of all humankind. You cannot act recklessly according to your feelings.”
“Master…”
At the pitiful sound of Scarlet’s voice, as though she were on the verge of tears, I offered a soft smile. She looked strong but was fragile inside; I wanted her to steel herself so she would not fall before the Demon King Kai-rak.
When the final battle truly began, I could no longer remain myself. The moment death claimed me, Kai-rak would seize control of this body, and there would be no mercy in his hands.
I gazed at Scarlet with warm eyes. That child, my disciple, the woman I loved—I believed she could break my chains and set me free.
Yet Scarlet was still not ready to fight. Her eyes were filled with hesitation and turmoil. Those trembling blue pupils looked as fragile as glass on the verge of shattering.
“You always told me, didn’t you? That a Hero grows strong only when they possess the right heart.”
The fragile atmosphere around Scarlet changed in an instant. Her blue eyes now burned with fierce determination.
“You said that if we strive to uphold our convictions, we can become endlessly stronger.”
Scarlet, radiating absolute resolve. She slowly approached me, releasing an overwhelming aura that blended mana, magi, and holy power.
“My conviction is that I will never abandon you, Master.”
A sharp crackle split the air as powers of opposing natures collided and sparks flew wildly. I felt satisfied. With strength like this, defeating me would be no great feat.
Witnessing power great enough to destroy me—someone neither god nor the Evil God could kill—I found peace of mind even as my heart ached for my disciple. My destruction now seemed entirely possible. Yet saving me would be an almost impossible task. It was like challenging the unattainable.
I knew too well how crushing the despair would be for someone who had staked everything on the impossible only to fail—how bitter the aftertaste would linger. My past self overlapped with the girl before me.
Still, I had to believe.
I believe in my disciple. I believe in Scarlet. If her own master did not believe in her, who would? As her teacher, I had to trust her no matter what—even if the goal was impossible.
“I respect your conviction. But… it will not be easy.”
At my warning, Scarlet’s eyes grew even more resolute.
“Since the day I became the Hero, I have never once believed it would be easy.”
There was no need for more words. I had seen her unyielding will. From now on, my only role was to watch the ending my disciple had chosen.
I looked at the friends standing before me. They all seemed to understand that the time for battle had come. Seeing their grave expressions, I spoke.
“All right. Enough talk. Now we speak with our strength.”
With those words, I rose from the throne.
Each step I took sent powerful magic swirling through the air, making the atmosphere itself tremble. Dark purple aura, brilliant holy power, and blue mana poured from my body, mixing together and sending sparks flying in every direction.
I deliberately radiated killing intent toward the heroes, issuing a warning.
“I am strong. You had best not lower your guard.”
“Master… one last time… is there truly no other way?”
A strange intensity filled Scarlet’s blue eyes.
“Yes. This is the fate we share. If I win, humanity perishes. If you win, humanity survives.”
After countless regressions, each ending in despair and a new beginning, my final struggle to break this cursed loop was about to begin.
“I will not run. A Hero is one who protects their beliefs.”
Hearing her repeat the words I had once spoken, I thought how much she had grown, how truly proud I was of her. And I dared to hope that this child could finally end my curse.
“Then, since you all seem ready… I will fight with everything I have.”
The consciousness of the Demon King Kai-rak wrapped around me. I slowly lost awareness.
When I regained consciousness, it was because of unbearable pain.
“Cough… Ha… Ha…”
The moment I opened my eyes, the agony was so intense I could barely speak. A groan slipped out before I could stop it.
“Ugh…”
“You mustn’t move, Kai.”
Cecilia was healing me. Blood trickled down her forehead. I tried to lift my right arm to wipe it away, but—
“Keuk…”
My right arm was twisted at a grotesque angle. In fact, aside from my left arm, there was not a single uninjured spot on my entire body.
“Stay still! The bleeding is severe!”
Looking at the tearful Cecilia and Scarlet, I laughed bitterly.
“So I lost in the end…”
Only then did the truth sink in. My defeat. The salvation of this world. And the moment of farewell with the people I loved.
I was not afraid of death itself. What terrified me more than death was—
“Master…”
the future of Scarlet, who stood before me crying. It would surely devastate her. I knew better than anyone how bright and cheerful she had been before becoming the Hero. And because she had once dreamed of a future together while courting me, I feared she would blame herself for my death.
The image of my beloved Scarlet trapped forever in the guilt of having killed her master and the man she loved with her own hands frightened me far more than dying.
“Hehe… kugh!”
I tried to endure the pain and force out a villainous laugh, but my broken ribs stabbed into my lungs and stole my breath.
“D-don’t talk! You’ll really die!”
Scarlet and Cecilia with tears brimming in their eyes, and all their comrades wearing the same sorrowful expressions—it broke my heart.
This was supposed to be a day of celebration. The day the heroes defeated the Demon King who could have destroyed the world. Yet it pained me deeply that none of them could smile.
I feared today’s events would leave scars that lasted a lifetime, that they would come to regret it in the years ahead.
“Cough… What a shame… I was so close to destroying the world… cough…”
“Don’t say anything!”
“Kai…”
“Hyung!”
“Master! Please stay still!”
Every time I spoke, blood rose in my throat, making it nearly impossible to talk. My body… this is the end… Just hold on a little longer…
Until now I had always wished to die quickly, but in this final moment I wanted to live just a little longer—for the sake of my good friends.
“Ah… it’s such a shame… I could have… destroyed the world…”
I had to play the villain until the very end. Kind-hearted Scarlet shook her head fiercely.
“Don’t lie! Master… you wanted to protect the world, didn’t you?! That’s why you trained me to be strong and helped Cecilia awaken! You did it for this world!”
The children looking at me with tears in their eyes… It seemed my lies would not work after all.
“You can’t die! After the battle… after it was over, we promised to travel together, remember?! Why are you trying to die on your own?! If you die, Master… how am I supposed to go on living?!”
Watching Scarlet cry out in anguish, I lifted my relatively unharmed left arm and gently stroked her head.
“I’m sorry… Your worthless master… kugh… ha… ha… Forget me… meet a good person… and be… happy…”
“No! We made a promise! When everything was over… when it was all finished, we would be together! We promised!”
Seeing the tears fall from her beautiful sapphire eyes, my heart ached more than any wound in my body.
“Be happy…”
With those final words, I began to lose consciousness.
Ah… I wanted to smile at the end. It seems this is as far as I go.
“Master?!”
“Hyung!”
“Kai!”
“I-I’m… fine… Just… losing consciousness…”
Everyone… thank you, and I’m sorry. May blessings fill the Hero and her party.
With Cecilia’s faint voice in my ears… I lost consciousness.