Multiverse Cross Ex

It was around the same time that Mitsuya completed the Fusion Reactor when Ataraxia received a distress signal from Tokyo Megafloat.

However, before that—

"I… I never thought I'd see this in my lifetime."

One of the senior engineers—an older man who had once worked under Nayuta—sank to his knees, his eyes shining with emotion.

And it wasn't just him.

The remaining scientists who had stayed behind after Nayuta's departure all fell to their knees.

Surely, this man was a god.

That was what they thought.

After all, Nayuta herself had once been regarded as a genius beyond comprehension—

A god-like figure in the scientific world.

Who wouldn't believe it?

She had single-handedly researched Hybrid Cores and implemented them into human technology.

Of course, she hadn't created them—the Vatlantis Empire had possessed them for a long time.

But that didn't matter.

Since her departure, only a limited number of Hybrid Cores had been left under Ataraxia's control.

Those cores had now been used for this groundbreaking process.

Yet, what truly shocked the scientists wasn't just the successful fusion reaction.

It was witnessing two entirely different core structures bonding—

Not just any bonding—

This was atomic bonding.

And did it have anything to do with the fractured sky they had seen?

By now, most of them had a clear realization—

Mitsuya was the pilot of the Machine.

'L-let's tell Reiri.'

Kei struggled to keep her composure as she tapped on her tablet, preparing to inform Reiri about the breakthrough.

However, before she could even type a word—

A sudden, urgent message popped up on her screen.

[Kei. This is urgent. Quickly summon Mitsuya now!]

That was all it said.

"Reiri?"

She muttered, her brows furrowing.

Her gaze shifted toward Mitsuya, who was still lying on the ground, smiling in exhaustion.

"Uhm… Mitsuya-sama."

While the others remained in awe, completely absorbed in the moment, Kei crawled toward him.

"Ha… ha… Ms. Kei? What's up?"

He responded between heavy breaths, looking at her as she raised her tablet—

Covering her face.

Mitsuya blinked, confused—

Then, his eyes dropped to the tablet.

Slowly, he read the message left open on the screen.

"Huh?"

Mitsuya sat up, his eyes scanning the tablet screen.

[Master, bad news. Tokyo Megafloat is under attack.]

'Huh? How?'

[Navi doesn't know. However, Tokyo Megafloat is indeed under attack.]

'That's ridiculous! Is that why Reiri is calling for me?'

[Yes.]

[Additionally, Master is forgetting something. Hida Kizuna—who, by extension, is Hida Reiri's younger brother—is a resident of Tokyo Megafloat.]

Mitsuya's expression twisted as he forced himself up, exhaustion weighing on his limbs.

"Ms. Kei, let's go."

"Hm."

He turned to the others, his voice firm.

"You lot, keep handling the situation here. I'll be back soon!"

Without wasting another second, he dashed out of the chamber.

Of all times, it had to happen now?!

Tch.

What the hell was going on?

An attack on Tokyo Megafloat had never happened in the original timeline he had known.

Tokyo had been attacked fifteen years ago—

And from that devastation, it had been rebuilt into Tokyo Megafloat.

Tokyo itself was supposed to be reclaimed sometime in the future.

But now?

Was this happening because he was here?

Had reality itself decided to fight against him?

Then if so—Fuck reality.

After about a few minutes, Mitsuya finally arrived back at the college and stepped inside.

"Mitsuya, you're finally here."

Uncharacteristically, Reiri called out to him—not with her usual commanding tone, but with something far more urgent.

The worry on her face was clear.

She had been pacing anxiously until he arrived.

And even Amaterasu's members had been summoned.

The moment he stepped inside, Reiri didn't waste a second.

"Mitsuya. Tokyo Megafloat has been attacked. Please, save them."

Her hand clenched into a fist.

She knew she shouldn't be asking this of him—

Not when she hadn't even fully trusted him before.

But now—

She needed his help.

Her brother was in Tokyo Megafloat, dammit!

And Amaterasu wouldn't be fast enough to get there in time.

"If there's anyone that can save them… it's you. The pilot of that machine."

Her words weren't surprising.

They all already knew.

"My brother… the people… please, help them."

Reiri—the woman who had given him trouble for the past month—

Lowered her head.

Even Amaterasu's members and Kei followed, their heads bowed in silent plea.

"Mitsuya-san."

"I'd like to request this of you."

"...."

Mitsuya fell silent.

This really was no joke.

The timing was too convenient, no matter how much he thought about it.

He had no choice but to accept.

But there was one problem—

He was drained after using Quantum Territory.

"Fine."

This wasn't just about helping them.

It was about maintaining his humanity.

No matter how detached Mitsuya may have been, he wasn't so cruel as to turn a blind eye.

His principle had always been—

"Do your best, and live the rest."

Thus—

"Navi, begin procedures. Summon Cross."

[...]

[Are you sure?]

"Hn. Do it."

[Understood.]

[Initiating startup.]

[Main systems online.]

As the activation process began, Mitsuya shrugged off his white lab coat, the fabric slipping from his shoulders.

Without a word, he handed it over to Kei.

"I'll leave this to you."

Now, he was left in his normal attire—a white shirt and black trousers.

The others watched him with silent gratitude before—

—CRACK!

DUM!

A shockwave rattled the entire building.

The ground trembled beneath their feet as something massive cast its shadow over them—blocking the light from above.

The silhouette of a titan loomed overhead.

A humanoid war machine, its metallic frame reflecting the dim sky as it descended onto the rooftop.

«Dimension Cross» has arrived.

Heck. It seemed like the machine itself was glad to be summoned once again.

"Navi. Transmit."

[Transmission in progress.]

Before their eyes, Mitsuya's body dissolved into particles.

Extremely curious, they rushed outside to the main grounds.

It wasn't just them—

Every student across campus, including those in class, hurried outside, smartphones in hand, eager to capture an image of the humanoid machine.

Inside Cross—

Mitsuya materialized within the pilot cockpit.

Settling into the extremely comfortable pilot chair—the type of ones that puts one to sleep—he then reached for the controls.

A 4K-resolution, 360° holographic display surrounded him—offering a full panoramic view of the outside world.

His hands reached for the controls—positioned perfectly on either side, fitted to his reflexes.

[Master, are you sure? Operation time has been reduced by 4 minutes.]

"…It won't take long to get there."

His fingers flexed over the console.

"We'll use Shuttling. No questions asked."

[...]

Quantum Shuttling—a system that would push Cross beyond conventional speeds, at the cost of operation time.

But that didn't matter.

If that was his decision, Navi would do its best to assist him.

[Understood. Quantum Shuttling activated.]

"By the way," Mitsuya said, leaning back slightly, "about what I asked… Recreating certain BGMs by scanning my brainwaves—how did it go?"

[Perfect. Navi has analyzed each one and successfully recreated Master's Playlist.]

A small smirk.

"Alright then… this situation calls for— Songs of Heroes ."

The cockpit hummed as systems powered to max capacity.

Outside. They'd seen it. Cross began breaking down into Particles.

Then—

The music began.

~Cross Your Hearts Exceed Your Limits~

And in that instant, with speed surpassing human perception—

Dimension Cross disappeared.