The Protagonist's Sister Is Actually The Strongest

”You’re…!”

As Beelzebub struggled beneath Anna’s overwhelming pressure, his gaze darted toward the figures stepping out from the Purgatory Portal.

A gigantic humanoid draconic reptilian demon covered in black scales, red eyes blazing, golden horns gleaming, and enormous sharp claws ready to rend.

Astaroth.

A massive saber-toothed cat-like demon with golden fur streaked by black lightning-like stripes, crimson eyes glowing, fangs shaped like bolts of thunder.

Aim.

A tall humanoid crow-like demon with sleek black feathers, piercing red eyes, four powerful wings, and four muscular arms.

Neberius.

A multi-armed centaur-like demon clad in crimson armor studded with sharp horns, wielding two enormous great blades.

Agares.

And finally, a towering humanoid demon encased in pitch-black armor from head to toe, crowned with massive black horns, gripping a large demonic sword with a crimson eye embedded in its blade.

Bael.

All of them were Death Apostles, members of the same group he once belonged to.

Death Apostles he had deceived, manipulated, and ultimately sacrificed.

They had changed dramatically since he last saw them, and their power radiated far greater than before.

Ki surged from their new, strengthened bodies.

They no longer required vessels to sustain themselves; they were powerful enough on their own.

Especially now that they were Anna’s Familiars.

”Hoh, what do we have here?” Bael asked, gripping his sword tightly. ”You said you had a surprise for us, but this? It’s more like a gift!”

”We meet again, Beelzebub,” Agares said coldly.

”Yeah, damn bug…” Aim growled, baring his lightning-shaped fangs.

”So you came all the way here to kill Anna?! Are you fucking stupid or something?” Astaroth demanded, anger rising in his voice.

”He clearly lacks a brain at this point, CRAAH!” Neberius shouted.

”Why are you…?! You’re alive?! How?! This is…!” Beelzebub stammered, confusion and frustration twisting his features. ”You’re working for a human now?! This is ridiculous! What has happened to your pride?!”

”Pride?!” Agares shot back. ”There’s no point in pride when we were nearly killed and then sealed by her. I can’t say I enjoy it, to be honest, but her treatment of us has been far better than yours, old friend.”

”You used us and discarded us the moment we were no longer useful,” Bael said, voice low and dangerous. ”We believed you would help us all gain new vessels. We surrendered our souls and powers for that purpose. Yet you used our deaths to fuel your damned plan… I thought we were alike, Beelzebub. That we worked together to forge a new world for demons. But we are clearly different. You’re a selfish bastard who has never cared about his fellow demons at all! A traitor to our very race!”

”Y-You dare call me a traitor to the Demon Race?!”

Beelzebub screamed in fury, indignation burning through him.

”Your deaths were necessary! If only she and her damned group of humans hadn’t interfered at the last moment, if that chimera bastard hadn’t tried to steal everything I worked for I could have achieved greatness! Incredible things! With that power I would have…!”

”What would you have done?!” Aim roared. ”You’re only obsessed with reclaiming the throne Uroboros took from you! You never cared about us!”

”The Titles of Death Apostles carry meaning for us,” Astaroth said fiercely. ”Our group wasn’t created just to fulfill personal desires. Our entire congregation existed for a purpose!”

”To bring back and recreate our Demon Worlds…” Bael continued, his pride and aura surging. ”To build a utopia for the demons lost across worlds and for those still clinging to life in the ruins of broken realms…! Did you ever spare a single thought for our fellow tribes and their suffering?!”

”Hah…”

Beelzebub lost all composure, a twisted smile spreading across his face.

”Hahahah… You’re all pathetic!”

He bared his sharp jaws in mockery.

”What did you say?!”

Bael’s demonic sword flared with immense power.

”You’re all demons! Why do you care about the well-being of others?! Our fellow tribes?! The ones who suffered and died?! Come on, our homes?! None of that matters anyway!”

Beelzebub laughed loudly, his voice dripping with scorn.

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”If you’re a real demon, you should only care about yourself! You fucking idiots sealed your own fates by acting like sentimental fools! Who cares about other demons, tribes, legacies, or homes?! That’s just weakness! We are special because WE SURVIVED! Don’t you understand?!”

As Beelzebub ranted, every demon facing him grew more enraged. Anna watched in quiet surprise. She had never seen this side of the Death Apostles in the novel.

”So that’s what you truly believe…” Bael said slowly. ”Very well… We won’t waste any more time.”

”Unlike you, we don’t forget our pasts,” Astaroth added. ”We don’t forget the families we had or the people we loved.”

”We might be foolish, or you might call us useless, but…!” Neberius growled. ”At the very least, we have one another, while you have no one!”

”Perhaps we were trampled,” Aim said, ”but we might have found a worthy leader instead of the sorry excuse you were.”

The demons turned their gazes toward Anna, making her feel strangely flustered.

”H-Huh?” Anna had hoped they would simply tear each other apart, but the situation had spiraled far beyond her expectations.

Despite their rough attitudes, the demons had already begun to respect her more than Beelzebub, at the very least.

And they even considered her a ”worthy leader”!

”Dammit, what the hell? Hahah…”

Beelzebub laughed again, glaring at them with manic intensity.

”If you’re going to throw away your lives against me, then come and fight!”

As he roared, his wounds closed and his Aura exploded outward into a gigantic swarm of thousands of insects.

”Alright, guys, you’re free to do whatever you want to him,” Anna said calmly. ”Nemesis, go help your new friends too. Be nice to them.”

”GRAAAH!”

Nemesis roared, thrilled to finally fight again.

He and the other demons charged forward. They had no time to question what the creature was—they simply joined the battle against Beelzebub’s swarm-like aura.

”RAAAHHH!”

Aim bellowed mightily. His body surged with demonic golden and red lightning as he swung his massive claws, unleashing explosive thunderous storms that tore through the swarm.

BOOM! BOOM! BOOM! BOOM!

He opened his jaws wide, ripping apart the insectoid monsters. Even when they detonated against him, he endured, his body having grown far tougher during this journey.

”BEELZEBUB, CRAAAH!”

Neberius flapped his four enormous, black-feathered wings, unleashing a rain of giant black feather projectiles. They pierced the fly’s aura and detonated in bursts of black flame.

BOOM! BOOM! BOOM! BOOM!

Neberius soared through the sky, dodging incoming strikes while releasing more feathers until hundreds formed a deadly swarm of blade-like projectiles.

”YOU THINK YOUR DAMN AURA CAN STOP US?!”

Astaroth roared, expanding to his largest size and slamming his fists into the enormous insectoid demon god aura. Each strike weakened it further.

BAAM! BAAM! BAAM! BAAM!

”GRRRHHH…!”

Beelzebub groaned in fury, struggling to hold them back, but steadily losing ground. Though he had fully healed, his power had not increased.

”I cannot grow stronger?!”

He quickly realized he had reached the absolute limit of his Demonic Rebirth. His body and talent were simply not strong enough to continue advancing.

”What’s wrong? Flustered?”

”Ugh!”

SLASH! SLASH! SLASH! SLASH!

A barrage of crimson demonic energy slashes struck Beelzebub. The giant insectoid tried to block with his arms and barriers.

Despite everything, he remained larger than the demons!

Yet he had gravely underestimated Agares.

”Fool!”

”{Demonic Crescent Moon}!”

The attacks fused into a single gigantic crimson crescent slash, cutting through Beelzebub and severing three of his arms in an instant.

SLAAASH!

”AAAAGGH?!”

In desperation, Beelzebub kicked Agares with full force, sending the centaur-like demon crashing into the sea below.

And yet…

”Fight me, Beelzebub! You ravenous traitor! You loathe Uroboros, yet you are just as treacherous as he is!”

Bael appeared above him, swinging his massive demonic sword, a weapon forged by Anna using her own powers. Though she could not restore his original blade Gram, she had crafted a copy: an enormous black sword with a crimson eye at its center, made from demonic metal refined with her own Demonic Ki.

”{Abyssal Descent}!”

Beelzebub tried to resist with barriers, arms, and aura, but Bael’s raw strength overwhelmed him.

CRAAASH!

The downward slash cleaved through everything, cutting halfway through his torso.

”GRUUAAGH?!”

Beelzebub vomited blood and screamed in agony, a guttural sound escaping his insectoid jaws. At the same moment, Agares reappeared behind him and unleashed the same technique again.

”{Demonic Crescent Moon}!”

SLAAASH! SLAAASH! SLAAASH!

Multiple times!

”I-IMPOSSIBLE…!”

In that instant, Beelzebub began to realize he was being overwhelmed, by the very demons he had always looked down upon.

The humiliation burned deeper than anything Anna had done to him.

”T-THIS CAN’T… THIS CAN’T BE HAPPENING TO MEEEE!”

Lucifer and Mammon’s power surged through him as he tried to regenerate, yet…

POOF!

”H-Huh?!”

His eyes widened in horror. The power vanished completely, sealed away. It never even reached him.

He glared at Anna. She smiled back.

”Nuh-uh. No more borrowing power from other Archdemons, not on my watch.”

Her Cosmic Aura had already formed a bubble around them all, cutting off the flow of power from Constellations to their Avatars.

”Y-You fucking bi—”

”RAAAAHHH!”

CRASH! CRASH! CRASH! CRASH!

Before Beelzebub could finish, his body was pummeled into fragments by the rampaging Demon King, Nemesis.

The fly tried to regenerate once more, but…

”I-I don’t have more demonic energy?!”

Despair flooded him completely.

”Hmm, it looks like the Constellations didn’t even send much power anyway…” Anna laughed from a distance. ”Maybe I shouldn’t have bothered blocking it? It seems they only used you to get here. After you brought the Demon Army and their Avatars, they stopped caring about you, Beelzebub.”

”W-What did you say?!”

Beelzebub’s eyes welled with tears. Fear and despair overwhelmed him, and he began to cry.

”Look at this bastard, he’s actually crying?!” Astaroth roared in disgust.

”Pathetic little shit, and you call yourself a demon?!” Aim spat.

”CRAAH! Piece of shit!” Neberius sneered, spitting in his face.

Bael and Agares glanced back at Anna.

”Anna!”

”You decide his fate.”

They thought she might spare him and force Beelzebub to join them.

But she knew they would never get along.

And honestly, she didn’t care much about a pathetic fly.

”He’s all yours, boys.”

She smiled devilishly, letting her demonic side show.

The demons grinned in response!

”Stop…! G-Get away from me!”

Beelzebub screamed in terror, unable to defend, regenerate, or fight back. He watched in horror as the demons he had humiliated, used, and betrayed tore his body and soul apart and devoured him.

”GRUUUAAAHHH!”

Crack, crack…!

CRAAASH!

As his soul shattered and was consumed, every Death Apostle grew stronger. Their forms evolved into even more powerful versions of themselves.

”Who would’ve thought that bug would help us evolve, CRAAH!” Neberius laughed.

”Hmph, serves him right…” Bael said coldly.

”Hahahaha! I’m so strong now I could slaughter a million humans—I-I mean, monsters!” Aim corrected himself quickly.

”Good,” Anna nodded. ”Now come with me… The real threat still remains. You’ve all grown decently strong, so I’ll be counting on your strength from now on. Don’t disappoint me.”

”We won’t!” they roared in unison.

In that moment, Anna had secured their absolute loyalty.

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