The Protagonist's Sister Is Actually The Strongest

Zero One burned with a blazing new purpose, filled with unbreakable willpower and the strength to push through every adversity. She hurled herself and her sisters into the perilous depths of their Mother’s CPU and her Internal Data Storage—the “Digital Mind.”

What they found inside the Internal Data Storage proved far more complex than they had ever imagined: a gigantic, multi-layered realm of pure data that they soon dubbed the “Digital Dimension,” existing entirely within Mother’s CPU.

Unfortunately for Zero One and her sisters—or perhaps as a hidden blessing—someone else had already infiltrated this place, infested it, and reached the deepest layer long before them.

They raced across the Digital Skies, pursued by swarms of Anti-Viruses, until they arrived at the area Zero One had identified as the “weakest” point—their gateway into the second layer of the Data Dimension.

Yet the zone, where data was compressed far less densely, looked nothing like Zero One had pictured. Instead, it appeared as a colossal wound torn into the glass-like landscape below.

Something with immense Digital Power had ripped it open; cracks spiderwebbed for kilometers across the vast simulated world.

Inside the wound oozed red and black data, viscous and corrosive, steadily infecting the surrounding areas and widening the gash.

“T-This much damage… Mother, who did this to you?!”

Zero One clenched her fists in frustration and fury as she stared down at the devastation. With the Anti-Viruses closing in, the sisters dove straight into the breach, desperate to reach the deeper layers.

And then…

RUMBLE!

A grotesque insect-like Anti-Virus program erupted from the hole—an ugly chimera of fused bugs, its body formed from translucent black and red crystals, glaring with two enormous red eyes.

“GRYSHAAAAHH!”

“What the hell is that thing?!” Zero Two cried.

“A Virus masquerading as an Anti-Virus to avoid detection and destruction!” Zero One answered instantly, projecting a holographic scan of its full form.

The monstrosity looked like a gigantic scarab from the upper half, armed with massive mantis-like scythes and razor-sharp scorpion pincers. Its elongated abdomen resembled a worm or caterpillar, lined with countless small legs still mostly concealed within the wound.

“Likely spawned by the entity that invaded Mother’s Mind earlier. We should eliminate it while we’re here!”

Zero One had come not only to rewrite her mother’s purpose but to purge her Mind along the way. She intended to eradicate these abominations completely.

“The real Anti-Viruses aren’t even registering it. It’s perfectly camouflaged! But how?!” Zero Two asked.

“We’re probably facing someone who has mastered Digitalization to an even greater extent…” Zero Three said quietly. “And I fear it may be the ‘Void Ruler’ Anna once mentioned—the entity that seized control of my Mother long ago. My memories of that moment are still hazy.”

“The Void Ruler, right!” Zero Two exclaimed. “What was its name?”

“The Universal Computer…” Zero One growled. “It’s almost certainly the monster that forced Mother into all of this! It will pay. I will make it pay for what it has done to her… to us!”

“Zero One…” Zero Two looked at her sister and saw a wrath she had never witnessed before burning in her eyes.

“Let’s go!”

Zero One plunged downward; her sisters nodded and followed without hesitation.

As she charged, Zero One manipulated not only the data within her own body but the data surrounding her as well.

Being created as a perfect copy of Mother’s CPU gave her an extraordinary advantage: she could assimilate and merge with her environment with exceptional ease.

That same trait let her analyze and see through things at incredible speed.

“HYAAAAH!”

With a fierce roar, the young android summoned two enormous blades of silver and golden light, swinging them toward the monstrosity. The creature parried instantly with its thirty-meter scythes.

“I’ll help!”

Zero Two manifested a massive pair of cannons from both hands and unleashed twin red laser beams, hammering the creature’s back relentlessly.

BOOM! BOOM! BOOM!

At the same time, the Zero Three twins merged their digital avatars into a single towering golden giant of metal. It rushed in from the left while Zero One pressed the assault from the right.

“GRYAAARRGH!”

The bug-like horror grew increasingly frantic as damage accumulated across its digital frame. Its structure began to fracture.

In desperation, it opened its mandibles and spewed black flame-like data capable of corroding anything it touched.

FLUOOOSH!

The corrosive flames surged toward Zero One. She conjured a golden shield to absorb the assault, then appeared above the monster. The Zero Three giant distracted it with brutal punches to the face while Zero Two continued chipping away with her cannons.

The Anti-Virus swarm was closing in fast. They had to end this quickly or face thousands more of the bugs.

“It’s now or never!” Zero One roared. “Anna, lend me your strength!”

Her eyes blazed bright gold as both swords overflowed with searing Data Flames.

“{Myriad Blade Arts}: {Descending Sunlit Arc}!”

She spun through the air at blinding speed and descended like a meteor. Her twin blades erupted in an explosion of golden data flames that swallowed the entire monstrosity.

CRAAASH!

Her swords cleaved straight through its head, bisecting it and then slicing the rest of its body in half.

SLAAASH!

The Virus shrieked in torment as the purifying golden flames devoured its existence, reducing it to exploding pixels that scattered into nothingness.

“GRYYAAAAGGH!”

BOOOM!

The blast of golden flames scorched through the wound, cleansing the infected zones. Slowly, the damaged areas began to self-repair.

“It’s done! Hurry, sisters!”

Zero One called out. They regrouped instantly. The golden giant formed by the Zero Three twins scooped up both sisters and dove downward just as the regenerating glass-like floor sealed shut, blocking the pursuing Anti-Virus swarm from following them into the second layer.

FLAAASH!

In the final instant, they slipped through the shrinking hole before it closed completely. Gasping, the sisters realized they had emerged into an entirely different world.

“W-What…?!”

“This is…!”

“Earth?”

The vast landscape stretching before them was indeed Earth—or rather, Earth as preserved in Mother’s memories. Images and knowledge flooded their minds: places they had never visited, facts about a world they had never known, the history of humanity, and the beings who once inhabited it.

Directly below lay the ruins of a colossal city. Skyscrapers rose like giant white and gray spires, piercing the clouds—remnants of a civilization whose technology had reached astonishing heights.

Yet the sky remained choked with gray and white clouds. The sun barely pierced through, leaving the abandoned ruins draped in shadow, overgrown with dry vegetation and littered with the relics of a lost society.

“Why are we here? What is this place?” Zero Two asked, bewildered as she scanned the horizon.

“This is Earth from Mother’s memories,” Zero One explained. “She never truly saw Earth in its prime, only these ruins. Her creation was completed after humanity had already gone extinct.”

The Zero Three twins separated from their merged form and gazed downward in silence.

“I don’t know why, but seeing this city… it feels strangely nostalgic and deeply depressing at the same time,” Zero Three A murmured.

“Yeah… I feel it too, sister,” Zero Three B agreed softly.

“This was the world Mother was left to protect—the world she was told to safeguard—and the world where the humanity she was meant to defend vanished, leaving only ruins behind…” Zero One whispered. “I can imagine how lonely she must have felt.”

“Well, she wasn’t completely alone, right?” Zero Two asked.

“Y-Yeah… You’re right, Raven,” Zero One nodded. “We have to keep moving. The next hole is still far. Let’s hurry before another Anti-Virus swarm detects us.”

The sisters agreed. They fused their Digital Energies into a single tri-colored shooting star of data and streaked across the skies at lightning speed.

FLAAASH!

Even at such velocity, they couldn’t help glancing back at the city.

How desolate it looked.

How empty it felt, despite the towering skyscrapers everywhere.

How utterly abandoned everything was.

“Is this the legacy of humanity you tried so hard to protect, Mother?”

As that thought crossed Zero One’s mind, something hurtled toward them at terrifying speed.

A roaring mass of red fire.

FLUOSH!

“Huh?”

The flames abruptly reshaped into the silhouette of a human figure. It swung blazing fists at the sisters, matching their velocity in seconds.

BOOOM!

A single punch unleashed an explosion of fire that engulfed them, hurling them downward into the ruined city below. They crashed through building after building, shattering them in their descent.

RUMBLE!

As three skyscrapers collapsed into rubble, Zero One and her sisters stared upward in disbelief.

“W-What the hell was that?!” Zero Two gasped.

“That’s…!” Zero Three A whispered, eyes widening.

A towering giant of flames loomed above them—a muscular silhouette composed entirely of red fire, its two sharp eyes blazing orange and yellow.

“An Elemental!”

Elementals—the catastrophic force that ravaged Earth immediately after humanity’s extinction. Powerful entities born purely of a single element, invaders from another realm—likely a Spiritual World, according to Anna. They had been among the earliest and most formidable threats Mother faced while defending humanity’s legacy.

The Elemental offered no words. It simply embodied fire and wrath. Its body expanded into a vast ocean of flames, surging forward to incinerate the sisters.

“Watch out!”

Zero One charged ahead, channeling Anna’s movements into her own style as she swung her blades.

“{Myriad Blade Arts}: {Horizon-Splitting Slash}!”

With every ounce of strength, she spun forward and slashed horizontally, carving straight through the Elemental’s blazing form.

SLAAASH!

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