The Protagonist's Sister Is Actually The Strongest

“If you don’t come, then stay here and torment yourself for eternity. End your life if you’re so desperate. I won’t grant you the swift release you crave.”

As the leopard walked away, the dragon remained behind, drowning in despair.

He didn’t know what to do.

But eventually…

He started to follow him.

“What’s your name?”

“Aim. Yours?”

“…Astaroth.”

“A-Astaroth?! I knew it was you! You’re the Demonic Dragon—one of Lucifer’s strongest generals!”

“Yes… that is what they call me…”

“You sure don’t look like the legends, though.”

“HAH?!”

“I thought you’d be, like, a kilometer tall. You’re barely three times my size…”

“I-I’m only conserving my energy. I can get really big, I swear!”

“Uh-huh…”

“So where… where are you taking me?”

“Where else? If you truly don’t want to serve Lucifer anymore, we need strong people like you. Have you heard of us?”

“Who?”

“The Death Apostles?”

“…!”

Astaroth’s eyes widened.

“You’re the ones trying to create a new world for demons?!”

“Lucifer seeks only to destroy worlds and devour their energies and stories. We aim to conquer one and reshape it into a true home—a place where demons can escape the 999 Hells and finally live in peace, free from his tyranny.”

“You’re insane… To go against him is…!”

“Hoh? Scared already? I guess you’re still his little pet after all. Does he give you tasty treats? Does he pat your head and call you his favorite?”

“S-Shut up! I am… No, I’m not that anymore! I am not a pet! I am… a demon!”

“Hmph…”

Aim smiled back at Astaroth.

“If you’re truly a demon, then you know our cause makes sense, don’t you?”

“…”

“You’ve seen what his negligence has wrought—unchecked power, tyrants running rampant, starvation, and poverty. The Hells once brimmed with resources. Now they’re stripped bare or hoarded by the Generals and Thrones. Everyone else must either join his endless wars and die, or starve. This cannot last! How did we ever crown that monster our King?”

“He’s… always been King. There has never been another. To defy him is simply…”

“Insane? Well, yeah—we’re all insane! You think we have any screws left? They’re all loose and gone! We’re fucking tired!”

Aim stopped. Ahead, Astaroth spotted a large cave sheltering a bustling camp filled with demons of every kind—beast-like, insectoid, and humanoid—working side by side.

He even saw children playing, and for the first time in eons, something stirred deep within Astaroth’s heart.

“Y-You have children?! I haven’t seen any in ages…”

“We do our best to raise them, but resources are scarce… So? Will you join us? Or… if you refuse, we’ll have to kill you right here.”

Suddenly, several other demons emerged behind Aim. Among them, Astaroth recognized a few former fellow Generals.

Bael, Agares, Neberius…

“I brought you to our base, so we can’t let you leave, Astaroth… But we know how strong you are. You could kill us all…”

“You really gambled bringing this fat ass here, damn cat,” Agares growled.

“Astaroth, huh? First time I’ve seen him in a hundred years…” Bael smiled.

“CRAAH! Are you joining or what?!” Neberius demanded.

“…”

Astaroth studied them. They were no weaklings.

They were powerfully strong.

If they all turned on him, they could kill him—quite easily.

“Hah… I don’t have much choice now, do I?”

Though he spoke those words, Astaroth had already decided to join the moment he saw the children. If they were fighting to protect these young souls, they could not possibly be worse than Lucifer.

“Welcome to the team!” Aim said. “You’re starting your job right now. Go over that mountain and bring us some food! Or else, we’ll kill you.”

“HAH?!”

Astaroth glared at them.

But then he noticed the children peeking out from behind the others.

“Uncle Neberius, who’s that?”

A little, red-skinned demon girl tilted her head, staring at the massive dragon.

“A big, scary dragon! Don’t get close, CRAH! Or he’ll eat you up!”

“R-Really?!”

As the girl gasped, Agares sighed.

“Come on, kids, back to the village. This isn’t a place for you.”

“But we want to see the big dragon!”

“Can’t we climb him?”

“Tsk! These damn kids have no sense of danger! How are they supposed to survive the hells?” Bael complained.

“Please, please, please!”

As the children begged, Astaroth felt overwhelmed.

“Ugh…”

He groaned and sat on the ground. The kids cheered and happily climbed onto his scaled body.

“Wooow!”

“It’s super high from here!”

“Heheh!”

“…”

Though Astaroth looked visibly annoyed, a small smile tugged at his lips.

“Hey, this bastard’s got a soft heart, doesn’t he?” Neberius remarked.

“Yeah, he’s easy to manipulate,” Aim laughed.

“Now go find us food, or the kids will starve!” Bael ordered.

“…Dammit, fine! But you’d better give them a good share, you hear me?!”

Astaroth gently set the children back down, spread his wings, and flew off.

After hours of foraging, he returned with the massive corpse of a two-headed demonic wolf and a black tree heavy with red, head-shaped fruits.

“Wooow! It’s him!”

“Uncle Dragon!”

“Uncle Dragon is back!”

“He is?!” Aim asked.

“W-Wha…? He brought so much food, CRAH!” Neberius exclaimed.

The group rushed out of the cave as Astaroth dropped his haul onto the ground.

“Eat the fruits. I’ll cut some meat for you brats.”

Using his sharp claws, Astaroth sliced the beast into large portions and cooked them with his fiery breath.

“Oooh!”

The children enjoyed their first real feast in years.

Aim watched as the rest of the village gathered around Astaroth. The dragon became popular in an instant.

“Hmph… You pass the test, newbie. Welcome to the Death Apostles.”

“Thank you… I won’t disappoint you!”

As Astaroth beamed with happiness and looked even more foolish, Agares and Bael glanced at Aim, raising their eyebrows.

“Are you sure about this?” Bael asked.

“This guy’s a fucking idiot. Look at his face…” Agares muttered.

“He’s good with kids… Anyone who’s good with kids gets a pass from me…” Aim sighed. “That’s rarer than you’d think among high-ranking demons.”

Years passed. Battle after battle, Lucifer’s forces hunted them across countless worlds. The Death Apostles fought desperately to claim new lands, only to be driven back again and again.

In time, they became part of the Cosmic Records—beings woven into the cycles of Apocalypse and Awakening, invaders that worlds had to repel.

Sometimes they won, claiming a planet for themselves, only for Lucifer to descend and steal everything once more.

They never knew lasting peace…

Yet Aim, the Death Apostles, and especially Astaroth never gave up.

They stayed together, fighting to survive this cruel universe.

Aim still remembered the day Astaroth saved his life, single-handedly defeating a powerful Demon General sent to take his head. Both were left broken and bleeding. Astaroth had lost his wings, one leg shattered, his jaw nearly dislocated.

“B-Bastard, you almost died…!”

“Well, what’s wrong? You have my back, and I’ll have yours. Alright?”

“What?!”

“We’re friends, aren’t we, Aim?”

“…But we’re demons! Demons don’t have friends, idiot!”

“Gahahahah! Maybe. But we aren’t exactly normal demons!”

“You fucking idiot…”

Those memories burned through Aim’s mind, his eyes blazing bright gold.

“ASTAROTH!!!”

He roared with everything he had. His entire body transformed into pure electricity.

FLASH!

In an instant, he reached Lucifer, shocking everyone.

He had gone far beyond his limits.

“{Infernal Thunderstorm}!!!”

RUMBLE!

A cataclysmic explosion of crimson, golden, and purple lightning erupted as Aim became pure elemental fury—something he had never achieved before.

BOOM! BOOM! BOOM! BOOM! BOOM!

“NNNGRAARGH…?!”

Lucifer howled in agony as lightning fried his heads from the inside.

“A-Aim…?!”

Astaroth’s eyes widened as his friend seized him in lightning form and dragged him to safety. They fell from the sky together as Aim returned to normal.

“YOU FUCKING CAT…!”

Behind them came Lucifer’s furious roars and the thunder of his monstrous heads drawing closer. Astaroth stared in disbelief.

“You… saved me?”

“Tsk, of course I did!”

“But… why?”

“Because… we’re friends, right?”

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