The Protagonist's Sister Is Actually The Strongest

As the King of All Evil took massive damage again and again, he frantically devoured his own summons to recover!

Yet even as he clung desperately to his vessel’s life, the four merged demons struck.

“BASTARD!”

“STOP DOING THAT!”

“FIGHT US, LUCIFER!”

“RAAAAHHH!”

Astaroth and Aim fused their draconic flames and golden thunder, unleashing a raging storm of thunderbolts and demonic blaze. Lightning-fast claw strikes followed, severing one of his heads.

Agares and Neberius merged shadow and swordsmanship into a single deadly force. Their knightly fusion flickered in and out around Lucifer, slashing with shadow blades and claiming two more heads.

Bael and Jeremias twisted space itself, guiding Anna and her allies through the chaos. They evaded lethal projectiles while carving through dimensions and blasting apart another head.

Finally, Nemesis and Legion roared, using Lucifer as a living punching bag. Dozens of gigantic mechanical arms hammered him with merciless blows.

“My heads!”

Lucifer’s power in his {Seven-Headed Demonic Dragon of Sins Form} relied heavily on those heads. Each one lost weakened him further, and once all seven were gone, he would become truly vulnerable.

Every Constellation possessed powers rooted in their stories and myths—and with those powers came weaknesses, though few ever had the strength to exploit them.

Of course, he could normally regrow his heads with ease, but—

FLUOSH!

“Ugh? I can’t regenerate them!”

Golden and pink flames burned fiercely along every severed neck, completely nullifying his regeneration.

This was Anna’s doing.

Her power of Hope and Love had flowed into her demons through the bonds they shared. That simple yet profound feeling in her heart had become even greater strength—power she freely gave to those willing to fight for what they loved.

“Looks like you’re losing, Lucifer!”

FLASH!

The Heavenly Empress appeared above him, teleported by Bael and Jeremias’s fusion. She swung her mighty katana, forged from her own mechanical armor through her Heavenly Imperial Armament Manifestation.

“Y-YOU BITCH!”

“{Demonic Nightmare Specters}!”

Lucifer summoned dozens of pentagrams, calling forth monstrous, nightmarish demonic specters that swarmed the Heavenly Empress.

They looked weak yet carried a vicious curse. The moment she touched them; her mind was dragged into endless darkness.

The void twisted into countless corpses of her loved ones scattered across the ground. Screams of agony filled the air—her people, her beloved son, her husband, and Anna.

This entire realm was a nightmare.

“I got her!”

Lucifer grinned through his remaining three heads. An eighth head suddenly burst from his torso, jaws wide open to devour the Heavenly Empress and steal her power.

This story originates from Royal Road. Ensure the author gets the support they deserve by reading it there.

But—

“That won’t work on someone like me.”

FLASH!

Her light shattered the nightmare in a single second. The power of Hope blazed forth, shining so brilliantly that Lucifer screamed, blinded by its radiance.

While he writhed in pain, the Heavenly Empress’s aura transformed into dozens of golden palms that slammed across his colossal body, spreading tiny cracks through his gigantic soul.

“{Heavenly Golden Palms of Hope}!”

BAAM! BAAM! BAAM! BAAM! BAAM!

“Ngh?!”

Lucifer retaliated with more specters, but they burned to ashes the instant they met her aura. “That won’t work anymore…!” Her furious roar shook the heavens and seas. Her aura erupted with overwhelming presence.

“{White Heaven Art}: {Thousand Palms of Buddha}!”

RUMBLE!

The sky trembled and descended. Massive white clouds formed into colossal palms that relentlessly crushed Lucifer’s body, giving him no chance to strike back.

“A-AGAIN?! UGGHH…!”

Desperate, he began fusing the beasts he summoned into monstrous chimeras and grafting them onto his own form, abandoning any regard for his shape in a bid to break free.

“RAAAAHHHH!”

With the fury of a world-destroyer, Lucifer roared and shattered the heavenly technique. Black and crimson energies devoured the palms one after another.

“{Heavenly Karma Blade Arts}: {Myriad Fold Soul Slash}!”

At that very moment, the Heavenly Empress answered. She channeled everything she had learned and awakened a deeper power—Karma itself.

An essence that governed most Murim worlds, perhaps even the origin of both Hope and the Demonic Cursed Seals. It ruled Fortune and Fate, shaped by actions, stories, origins, and the threads of past and future. Karma molded entire worlds in countless ways.

Just as it had created a savior like her, it had also created a destroyer like the Heavenly Demon.

She had learned long ago that she and her husband were Avatars of Karma, embodying Yin and Yang. Their titles echoed across countless Murim worlds.

Now, she drew upon that primordial power.

SLASH! SLASH! SLASH! SLASH! SLASH! SLASH!

A single strike multiplied into thousands. Lucifer felt his entire body being endlessly carved apart by an ocean of radiant, heavenly light.

“GRAAAAHHHH! D-DAMMIT! DAMMIT ALL!!!”

He cursed her and fought back with everything he had, punching wildly at the demons, Anna, and the Heavenly Empress. Each desperate blow pushed them away but only deepened his own wounds.

They leaped at him without pause, granting him no rest, no mercy, nothing.

“LUCIFER!!!”

Then the one who hated him even more than Anna roared. Song unleashed the full power of his Heroic Heart of Will—the same karmic force at its peak.

The boy who had sworn to avenge his father no matter the cost.

“T-THAT DAMN BRAT AGAIN—GAAAGGH?!”

Lucifer barely registered what happened before Song appeared right in front of him, teleported by Bael and Jeremias. Blazing punches slammed into two more heads, burning them with bright red flames.

BOOOM! BOOOM!

Just like the others, the heads refused to regrow. They remained as long, burning necks that crumbled steadily into cinders.

“I SWORE I WOULD AVENGE MY FATHER!!!”

Song’s roar made the heavens tremble. His battle aura surged, suddenly mirroring the figure of his father—yet formed entirely of crimson flames.

His wings tripled in size. Black and white feathers gave way to brilliant gold and red.

The power of the Phoenix awakened within him, as if an ancient bloodline long buried in the roots of the Bird Tribes had finally reignited.

The long-forgotten Phoenix Tribe.

“CAAAAAHHH!”

Song’s aura cried out like a mighty phoenix, unleashing a sea of willpower flames that washed over Lucifer and scorched him to the core.

Lucifer grew nearly powerless, his soul trembling, yet his will to destroy them burned hotter than any instinct for survival.

His pride ran so deep that he would endure any suffering if it meant tearing his enemies apart.

Song met his claws and tentacles head-on, punching blazing holes through his body and making regeneration nearly impossible.

BAAM! BAAM! BAAM! BAAM! BAAM!

“FUCKING… BRAT!!!”

Lucifer’s Demonic Cosmic Soul suddenly surged outward, attacking Song in the form of countless horrors.

Song did not face the monstrosity alone. Anna, the Heavenly Empress, and the demons stood with him, pressing forward and tearing deeper into Lucifer’s soul.

Their auras—demonic, holy, ki, mana—merged into one. With Song and Anna at the center, everything converged into a pure, seamless wave of crimson, golden, and pink flames.

FLUOSH!

With only one head left and unable to regrow more due to the limits of his transformation and its story, Lucifer was running out of options.

Anna smiled.

She was ready. Everything was ready.

It was now or never.

“Gram, let’s do this.”

She charged downward, dodging Lucifer’s desperate claws and tentacles as he fought for survival against so many powerful foes at once.

“WHERE DO YOU THINK… YOU’RE GOING?!”

Dozens of demonic beasts materialized to block her path. Having learned they were innocent demons he had twisted and corrupted, Anna’s fury burned hotter than ever.

“You think this will stop me?!”

With a world-shaking roar, her aura fused with her many swords. She swung them mercilessly against the beasts.

Just as before—

“{Heavenly Myriad Blade Arts}!”

Her aura transformed into a spiraling galaxy of pink flames shaped like countless cherry blossom petals.

She looked beautiful. Majestic.

And to Lucifer—utterly terrifying.

“{Blazing Loving Embrace}!!!”

SLASH! SLASH! SLASH! SLASH! SLASH! SLASH!

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