The Protagonist's Sister Is Actually The Strongest

Across all Worlds, Demon Kings were numbered; there weren’t endless Demon Kings after all; each one was a unique seed across the universe, created by mysterious beings to spread chaos and destruction and become a world’s ultimate boss, a natural enemy to all life, especially the intelligent beings of the worlds they appeared in.

Earth already faced its Demon King, and Bestia itself also had its own, Song Weisheng, the child of the Heavenly Demon and the Heavenly Empress. Demon King Seeds usually required a vessel, which would evolve into the Demon King by absorbing the seed.

Sometimes it was something the vessel desired; other times, it was something against their will. When the vessel itself wanted to become a Demon King, the evolution was flawless, and it would bring chaos and destruction as quickly as possible.

When the vessel was unwilling, however, and as long as they had enough strength of their own to resist, something different would happen: the Demon King would become incomplete, with a divided will, one of destruction and another that was the original vessel, constantly trying to fight back but slowly being consumed.

There hasn’t been any registered case of a Demon King managing to return to their previous form across the entire universe; once they turned into one, this would become their new body and form forever.

However, what Anna’s and Song’s parents were planning to do was go against all previously established rules across the universe.

RUMBLE!

The Mechanical Tree trembled, with its upper half gone, sinking into the ocean; what was inside of the massive mechanical construction was finally revealed.

The fiery phoenix made of golden and black flames that was made by the combination of the two Venerables’ powers and auras quickly turned back where it came from, facing the gigantic being that emerged.

“GRUUAAAAHHH!”

A scream of both agony and fury echoed through the entire ocean as the massive monstrosity rapidly crawled out of the mechanical tree.

The Seal that had been placed into it was already completely gone with that attack, and now, finally awakened once more, the Demon King aimed to end this world once and for all.

FLUOSH!

As its tremendous Aura erupted from its body, the dust covering it dissipated, revealing to everyone its true form and how gigantic it was.

Over three hundred meters of height, a fusion of both flesh, black and white feathers, and silver, blue, and golden metal.

The monstrosity spread out its massive wings, four of them, two white and two black, covered with metallic pieces, not completely just flesh and feathers. Its metallic feathers glowed brightly as it roared furiously at those that dared to seal him.

It spread out its two muscular, biomechanical arms; wires and veins could be seen through them, as massive and sharp claws adorned its hands, which had red-colored mechanical eyes on them, loading electromagnetic and demonic energy to fire deadly lasers from them.

FLAAASH! FLAAASH!

The two beams reached Song’s parents as the two Venerables rapidly combined their Auras together once more, shaping it into a gigantic black and white shield with the Yinyang Sign in the middle.

BOOOMMM!!!

As the two lasers hit the shield, the shield rapidly resisted, although it gained some cracks! Anna’s eyes widened lightly, realizing the tremendous power level of this Demon King, capable of even overcoming the power of the two Venerables combined.

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“So that’s why they merged their Auras right away…!” She thought at that moment. “Is he so strong because he possesses all of Song’s powers?!

Song Weisheng was chosen by Heaven as the Son of Providence, an unparalleled existence with powers that went beyond what any mortal or immortal could ever achieve.

However, he was still an infant when he was turned into a Demon King, and his powers never truly awakened in that time…

But when the Demon King Seed possessed him and it spread its power through his flesh and blood, mutating him into that being, his innate powers and talents were awakened.

RUMBLE!

Nonetheless, the Venerables also had their own tricks.

The Yinyang Symbol within the shield suddenly began spinning around; the energy it received was suddenly… Sent back!

“Yes! They did it!”

TRUUUMMM!!!

Anna smiled with excitement; she had spent some days showing her adoptive parents her many treasures and weapons, among them her Golden Dragon Shield.

This shield had tremendous power, capable of absorbing damage and then sending it back to the user.

After analyzing and learning its composition, they spent some time trying to recreate it, and this was the result.

A series of powerful artifacts and powers they could only unleash by fusing their powers as one.

And among them, this shield was made to reflect the Demon King’s deadly lasers.

BOOOMMM!!!

The beam went back at the Demon King, hitting his large bird-like mechanical head, blowing half of it off.

“GRAAAAGGHH…! GRAAACK…!”

The Demon King groaned in pain, vomiting blood and smoke. The Heavenly Empress became worried for a moment; Anna noticed how much she struggled to even bring herself to harm her dear son.

“Anna! When are we entering into the battle?” Song asked; he was growing impatient by her side.

“Patience! For now, harness your power into a single point, like we trained before, remember?” Anna asked Song.

“Okay!” The boy nodded, channeling darkness and light into his fingertips, constantly.

“Young lady, the rest of the group is fighting the machines coming from the Mechanical Tree, but it seems none of them approach us…” Fang Shuan said.

“They’re probably afraid of the Demon King; it’s not exactly their ally; it’ll probably also destroy machines if they get too close…” Anna said. “So, while it’s still dangerous that we’re facing such a monster, we’re safe from being attacked by machines for now…”

“I see…” Fang Shuan nodded. “Then shall I begin transforming?”

“Yes, prepare yourself,” Anna nodded.

CLANK! CLANK! CLANK!

In that moment, Fang Shuan’s entire structure began to rapidly transform, gaining mechanical body parts and becoming larger than ever before.

Anna, meanwhile, concentrated, trying to meditate as she watched her masters battle their son.

She had gained a lot of power in her latest battle, and she had little time to actually harness it and use it properly!

So right now, her priority was to do that, to rapidly refine this power and make it completely hers; her Aura began to rapidly grow, expanding constantly.

A sphere in her hands, the Morphin Core that the Rainbow Knights gifted to her, quickly flew towards her chest, merging with her Spiritual Body.

FLUOSH!

“GRRRHHH?!”

The Demon King instantly glared at Anna with its fiery red eyes, noticing the intense and powerful aura she was exuding, yet she only looked back at him, into the eyes.

The two met, and neither said a word.

“GRUUUAAAAAGGH!”

The Demon King roared, his shoulders transformed into gigantic cannons, charging demonic energy and electricity and firing two titanic beams at her.

Anna felt slightly surprised but closed her eyes.

BAAAM!

The beams hit a floating Yinyang shield again, absorbing the damage and then firing it right back at the Demon King once more.

BOOOMMM!!!

“GRUUUGH?!”

The Demon King groaned in pain again, roaring furiously at his parents, whom he could no longer recognize anymore.

The strategy was simple; the two Venerables knew of Song’s tremendous power as a Demon King.

So their best shot, aside from over exhausting themselves using powerful techniques, was to use his own strength against him!

“Anna’s a genius! Thanks for letting us analyze and learn how to materialize these shields; we can now fight against Song much better than we could have ever done before!” The Heavenly Empress said through telepathy, smiling a bit.

“Don’t get too excited; this isn’t over yet,” the Heavenly Demon whispered to her through telepathy. “We ended up exhausting a lot of our strength on our way here even with all the powers we’ve gained. We must use our power carefully!”

“I know…” The Heavenly Empress nodded. “Let’s continue this dance then!”

The two moved forward; the Demon King rushed back to them, using its massive wings to propel itself through the skies at immense speeds despite its massive body.

“RAAAAAHH!”

With a ferocious and mindless roar, the Demon King opened his jaws, firing another powerful beam, this one containing Heavenly Ki.

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