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

Sitting cross-legged on the tatami mat, Kagaya Ubuyashiki felt both helpless and nervous.

Persuaded by Kanae, he had decided to accept the injection of the Ghoul-3 solution.

Even though Haruto had said it wasn't a precious item, Kagaya still wanted to save the serum for other members of the Demon Slayer Corps.

When it came to his own body, he cared the least.

To him, he was the weakest among the Demon Slayers, incapable of fighting. He could only hide in the back and devise strategies for the others. Though he was called "Master," he never saw himself as more important than anyone else.

Moreover, Kagaya was well aware of his physical condition.

His frailty was less of an illness and more of a hereditary curse.

Everyone in the Ubuyashiki clan suffered from it.

Throughout the centuries, there had been attempts to cure it, but they all ended in failure.

Thus, Kagaya never held much hope.

However, Kanae was brimming with confidence.

The syringe pierced into Kagaya's veins.

As the Ghoul-3 solution was injected—

The members of the Demon Slayer Corps all widened their eyes in shock.

Before their eyes, the scars on Kagaya's face visibly faded.

The previously disfigured upper half of his face rapidly healed, his skin smoothing out to a normal complexion. His once pale, cloudy eyes began to regain color. Black pupils formed in his eyes, and under the sunlight, his pupils even reacted.

Witnessing this, the Demon Slayers were utterly dumbfounded.

They had some understanding of their Master's condition.

Even though the Flower Hashira had spoken highly of the serum, they had only dared to hope for a slight improvement.

No one expected that mere moments after the injection, his illness would improve so drastically.

After all, sickness strikes like a landslide but recedes like silk being drawn.

No matter how miraculous the serum was, they had never imagined such an exaggerated effect.

But the one who felt it the most was Kagaya himself.

A world that had been shrouded in darkness for so long now had light.

Then, blurry images began to take shape.

And finally—

Numerous familiar yet unfamiliar figures appeared before him.

For the first time, Kagaya Ubuyashiki could see what the members of the Demon Slayer Corps actually looked like.

Compared to what he had imagined, they seemed even better.

Without needing assistance, he stood up on his own.

Though he had never considered himself important, at this moment, Kagaya was overwhelmed with emotion.

His gratitude was evident.

Haruto simply waved his hand dismissively, signaling Kagaya not to dwell on it. The so-called "curse" of the Ubuyashiki family was merely a genetic disorder.

A congenital disease at the cellular level, which was why all conventional treatments had failed. The essence of the Ghoul-3 solution was to introduce RC cells that could activate the body's regenerative abilities on a cellular level.

Kagaya's condition was naturally nothing in comparison.

Healing him also served Haruto's personal agenda.

Although Kanae had introduced him—

Gaining the trust of the entire Demon Slayer Corps in a short period was still a hassle.

However, if he healed Kagaya—

Given Kagaya's unparalleled status within the Demon Slayer Corps, the one who cured him would undoubtedly be unconditionally accepted by its members.

Afterward, there would be no need for unnecessary persuasion.

After calming down, Kagaya composed himself again, though his gaze toward Haruto still carried immense gratitude.

Haruto then took out several more vials of the Ghoul-3 solution and handed them to Kagaya.

"These injections should be given to the Hashira. Kanae is an example before this, she was utterly drained from overusing her Breathing Technique."

Hearing this, Kanae smiled sheepishly.

Receiving the vials, Kagaya no longer knew what to say.

The aid this young man provided was beyond anything he could have imagined.

Haruto continued,

"Next, the Foundation's Mobile Task Force will conduct a thorough search for Muzan. In the best case, a few days; at worst, one to two months—Muzan will be eliminated, and the other demons will perish as well."

"Kanae should have already mentioned that we, the Foundation, have crossed over from another world."

"Thus, our only request to the Demon Slayer Corps is to establish a containment station here."

"I will open a gate at the Corps' headquarters that connects both worlds, allowing other Foundation personnel to come and work."

"We are friendly, but our existence must remain a secret to the outside world, for your protection."

Haruto laid out the Foundation's next steps.

As expected, Kagaya immediately nodded.

"I understand. The Demon Slayer Corps will fully cooperate with the Foundation's efforts, as long as it means the eradication of all demons and the destruction of Muzan."

After that, Haruto made his way to a room deep within the courtyard.

The headquarters of the Demon Slayer Corps was hidden deep in the mountains. To evade Muzan's pursuit, this location was already highly secretive.

It was the perfect place to set up the Foundation's station.

Inside the room, Haruto accessed his system interface, preparing to connect the worlds and open a portal.

Kanae and Shinobu followed after him.

Seeing Haruto, Shinobu was irritated.

"You spouted all that grand rhetoric, yet instead of staying to fight, you're leaving! How could you do this to my sister?!"

Butterfly Kanae quickly reached out to cover Shinobu's mouth.

What did she mean by "do this to her"?!

Haruto had only saved her, nothing more…

Haruto tilted his head slightly.

He had a feeling Shinobu was misunderstanding something.

But looking at her adorable, indignant expression—so different from the expressionless girl in his memories, he found it rather endearing.

"I would love to stay and fight alongside Kanae and Shinobu, but unfortunately, I cannot."

Shinobu was momentarily taken aback.

Especially when he called her "Shinobu."

That sounded so weird!

Why wasn't he getting mad?

Haruto continued,

"My world also has anomalies similar to Muzan, some even more terrifying. If I remain here too long, my world might suffer from their horrors, and countless people will die. But rest assured, the strength of Mobile Task Force; Wings of Freedom, is enough to deal with Muzan. There is no possibility of failure."

Shinobu: !

A wave of guilt nearly overwhelmed her.

The boy before her seemed to emit a soft, holy glow, so gentle it made one want to cry.

He was someone like their Master… perhaps even more so, someone who traveled the world, burdened with the lives of many.

Shinobu chastised herself for questioning him without knowing anything.

As she was lost in guilt, she heard Haruto say,

"If you're worried about your sister's safety, you could always persuade her to come with me, it's perfectly safe. I'll take good care of her. If you two sisters need someone to rely on, I'll take you both in—no need to worry!"

Shinobu: !

"MMMMPH! MMMMPH MMMMPH MMMMPH!"

If not for Kanae holding her back, Shinobu would have charged at Haruto for a fight.

Damn it, give her guilt back!

"Haruto, that kind of joke… Shinobu will take it seriously."

Kanae's pretty face turned slightly red as she spoke.

Haruto, however, composed himself.

"How could this be a joke? I've already said before, as long as Kanae is willing, she can always—"

Before he could finish, Shinobu threw a shoe at him.

Haruto swiftly dodged and laughed loudly.

This kind of fun was probably something only Haruto could appreciate.

The always expressionless Shinobu now looked completely flustered and exasperated. Her drastic emotional shifts made it impossible to associate her with being emotionless.

This contrast was truly amusing.

Uh… no wonder so many girls said Haruto had a twisted sense of humor—it wasn't an unfair accusation.

Once the portal opened and the connection between the two worlds stabilized, Haruto made his escape. All that was left behind was an angry, clawing Shinobu and a blushing Kanae with a racing heartbeat.

After returning to the main world, Haruto called in the Foundation's staff.

Even though Muzan hadn't been contained yet, they could already establish a connection with the Demon Slayer world.

Since they were setting up a base there, it was the perfect opportunity to launch a few satellites.

Once the satellites were in place, communication and surveillance would become much easier.

With satellite monitoring, locating Muzan would be much faster.

Capturing and containing Muzan as research material would also accelerate the Foundation's biotechnology advancements. Muzan, that scumbag, had no idea that an even bigger scumbag had his eyes on him—treating him like a bagged research specimen.

For now, the Demon Slayer world was on hold. The task of containing Muzan was handed over to the Mobile Task Force.

Any further plans for the Demon Slayer world would have to wait until Muzan was captured.

Haruto also planned to recruit the nine Hashira and Kagaya Ubuyashiki.

It was similar to how he had recruited Erwin and Levi from the Attack on Titan world.

These individuals had emerged as the best in their world, possessing an unyielding will to protect humanity and the talent to do so.

They were exactly the kind of people the Foundation needed.

----------------

A few days passed, but there was still no good news from the Demon Slayer world. However, Haruto received an unexpected LINE message.

Someone was requesting to add him as a friend.

The profile picture was a pink rabbit headband.

The moment he saw it, Haruto had a slight guess about the sender's identity.

After approving the request, the other side immediately sent a barrage of exclamation marks.

Rabbit: !!!!!

Haruto: A crazy fan? Sorry, but I'm a bit troubled by this.

Rabbit: I am NOT!

Rabbit: We worked together a few days ago…

Haruto: Oh! It's Kita-san! Hello, hello!

Rabbit: ?

Rabbit: Was there someone named Kita in the dating show?

Rabbit: I'm Sakurajima Mai! We even had a private conversation at the end of the show!

A palpable sense of resentment seeped through the text.

Haruto: I knew it was Mai, just wanted to lighten the mood.

Haruto: I still remember Mai's headband.

Rabbit (Sakurajima Mai): That's kind of annoying.

Sakurajima Mai: But… you actually remember me, and you're responding to me.

Haruto: Uh, Mai, you should have more confidence in yourself.

Haruto: As a woman, you're undeniably a stunning beauty. It's only natural to react.

Sakurajima Mai: Really? Then do you like—

Sakurajima Mai: Wait, no, now's not the time to steer the conversation that way!

Sakurajima Mai: I meant a response to my existence!