Mash-up Anime World: Creating the SCP Foundation to Contain Anomalies

Haruto's casual and indifferent demeanor only heightened the black-haired girl's anxiety. 

Even though Haruto had just demonstrated overwhelming combat prowess, human perceptions couldn't shift so quickly.

The world was ravaged by the Gastrea, creatures that had dragged nearly every surviving human into a state of deep-seated terror.

This fear was ingrained, impossible to erase in an instant. 

Nearby, trees were crushed under immense weight as several Gastrea emerged into view.

Their forms varied wildly, but the most striking was the one in the center—a monstrous amalgamation of multiple insectoid features, towering over five meters tall. It was the kind of sight that could shatter one's sanity. 

The black-haired girl's grip on her katana trembled slightly as she stared at the composite monstrosity. "A Stage Three Gastrea... How could something like this appear near the Monolith?!" 

Haruto glanced at her. Another unfamiliar yet oddly familiar term.

He'd ask about it later. 

In the next moment, under the girl's stunned gaze, Haruto merely flicked his fingers a few times.

A series of shattering sounds echoed, and the Gastrea disintegrated as if they were made of glass, crumbling into dust without a single drop of blood spilled. The particles lingered in the air for a moment before vanishing entirely. 

If not for the broken trees left in their wake, it might have seemed like a dream. 

Haruto wasn't one to wait for monsters to attack just to show off at the last second. As an O5 of the Foundation, he prioritized efficiency. 

The black-haired girl turned to him slowly, her expression dumbfounded. "Who... are you? Special forces? A mechanized human?" 

What she'd just witnessed defied everything she knew.

In her understanding, a Stage Three Gastrea required either a high-ranking Initiator or an entire squad of well-equipped guards to take down—and even then, the battle would be grueling.

But this? A flick of the wrist, and they turned to dust? 

Magic? 

Haruto, however, was more preoccupied with the growing list of unfamiliar terms. It seemed this world's human civilization had advanced in unexpected ways—even developing human mechanization. 

"First, could you explain what Gastrea are? And your name?" Haruto ignored her questions and posed his own, while sifting through his memories. 

"Huh?" The girl gave him a look that screamed, 'Are you kidding me?' Who in this world didn't know about Gastrea? 

Still, she answered—perhaps out of respect for his strength, or because she needed his help to return safely. 

"I'm Tendo Kisara. You... whatever. Gastrea are a new species of creatures that emerged in 2020. They're mutants born from hosts infected by the Gastrea virus, with terrifying infectious and reproductive capabilities. They evolve by consuming other organisms, absorbing their genes to develop abilities beyond biological limits." 

As Tendo Kisara launched into her explanation, the two began moving toward the towering Monolith in the distance. 

Her words jogged Haruto's memory. It wasn't surprising he hadn't recognized this world immediately—it was based on an old anime he'd deliberately forgotten. 

This world... was hell for little girls. 

Black Bullet.

This parallel reality was also set on Earth. In 2020, the Gastrea virus outbreak had unleashed the creatures, nearly wiping out human civilization.

The Gastrea were biologically superior to humans in every way. 

The remnants of humanity discovered a new metal, "Varanium," which could suppress Gastrea regeneration and pierce their defenses. They forged weapons from it and erected massive Varanium Monoliths.

Since Gastrea instinctively avoided Varanium, these Monoliths became humanity's last sanctuaries. 

But there was more. 

Children born to mothers who were pregnant during the outbreak had been exposed to trace amounts of the virus in the womb.

These children developed resistance to the virus and partial evolutionary traits, granting them superhuman abilities akin to the Gastrea. 

However, the virus still corroded them, albeit more slowly.

Once the infection rate exceeded 50%, they too would transform into Gastrea. 

These children were called the "Cursed Children." 

Due to the virus's effects, all Cursed Children were girls. By the current timeline—ten years after the outbreak—most were between nine and ten years old. 

Human society weaponized them as "Initiators" to fight the Gastrea, while simultaneously ostracizing and hating them. 

Recalling these absurd details, Haruto rubbed his temples. 

'Honestly, maybe this world should just burn.'

"Hey, if you're not a Civil Officer, want to join my security company?" Tendo attempted to recruit him. "With your strength, you could rise to the top ranks in no time." 

A powerhouse like Haruto, who seemed clueless about this world, was a treasure trove of potential. 

But Haruto didn't even hesitate. "Daka, kotowaru!" 

Why would he bother with this cursed world? He just wanted to observe briefly before severing the Red Pool's connection to it and returning to his own reality. 

...And maybe take a few lolis with him. 

Ahem.

That wasn't the point. 

Tendo was baffled by his refusal.

He seemed so clueless—shouldn't he be easy to manipulate? And wasn't her appearance deceptive enough? 

She glanced down. 

Her black sailor uniform, pleated skirt, and thigh-high stockings accentuated her long legs and flawless proportions. Even in her disheveled state, she had an air of delicate beauty. 

*Where did I go wrong?* 

Just as she pondered this, a boy came sprinting toward them. 

"Kisara-san!" 

Clearly an acquaintance. Seeing her unharmed, he sighed in relief. 

Haruto studied the boy. 

This was the protagonist of this world, Satomi Rentaro—a tragic figure burdened by a painful past, struggling to cling to hope in a grim reality. 

Tendo blinked in surprise. "Rentaro, are you insane? You just became a Civil Officer, and you don't even have an Initiator yet!" 

Satomi Rentaro smiled wryly. "I went to the company and found it in ruins. I followed the trail here." 

As they spoke, Haruto's gaze drifted elsewhere. 

They were on the outskirts of the Monolith, separated from the outside by a massive trench-like sewer. A broken bridge spanned the gap, and below... 

Haruto spotted signs of life. 

Who would live in such a dangerous place? 

The answer was obvious. 

The Cursed Children. 

His sharp eyes caught a few small figures peeking out from the shadows—tiny girls, curious yet fearful, watching from afar.