Multiverse Cross Ex

2:35 PM, South Pacific Ocean.

On this day. A portal tore open. A portal, an entrance to an alternate world, was torn open above the skies of the Southeast Pacific Ocean.

From the chaotic portal, mechanical beings made of steel and magic slowly appeared from within the portal, overrunning the skies with their numbers.

In numerical terms, there were definitely no less than hundreds.

It had been like this for fifteen years.

However, humanity too had been prepared for this invasion. It was something they'd expected to happen.

Yet, even if they had the necessary means of response to the AU invasion, they still had no idea when and where they'd appear.

But despite this, they were still quick in response to their appearance, with all Megafloat affiliated to Japan immediately noting their invasion.

Alarms blared, and red lights flashed across the command decks in Megafloats close to the area.

"Enemy detected! AU portal breach confirmed!"

"Confirmed visual on AU signatures."

"They're breaching at 12,000 feet and descending rapidly!"

"Deploy units!"

From their base. The commander of the closest base to the crack in space had given permission to sortie.

However, before they could even sortie their team, on the feeds, they had seen a change in situation.

It had happened, right behind the Army of the AU. A large, deep-blue crack in the diamond that was made behind the spatial tear of the invading force.

And from it appeared another machine, far different from the Army of AU or theirs or anything Dr. Nayuta herself had ever produced.

It was a large humanoid machine around ten meters in height, a similar height to that of the invading AU's Albatross. Yet, its features were more defined and refined than the AU's crude constructs.

As it fully appeared from the deep-blue crack in space, its armour shined with a mix of deep blue, black, and gold, with a mechanical blade of wings behind its frame.

"Restrictions Lifted."

Its voice was cold and mechanical, reverberating as its engines revved up.

This action alone had already caught the attention of the AU's army as they all turned to the new machine.

"[Tachyon Auto Recycler on. Wing Blade open. Line Set. Quantum Territory: Deployed]"

"[Dimension Cross. Max charge. Begin Annihilation]"

Its mechanical voice rang out again and, in a blur, faster than the eyes could track. Explosions erupted.

BOOM—!

Desperate, the invaders retaliated, unleashing a torrent of energy blasts and projectiles.

But the machine didn't evade. It didn't even flinch. Standing in place as their attacks struck the machine.

Yet, even though their attacks struck its frame with sparks and explosions flying. It didn't make a single dent on this machine.

As if it had waited for their turn to end, it then began its own counterattack like it had been a turn-based game.

BOOM!

One by one, the AU constructs exploded in dazzling bursts of light, flames, and smoke.

Pieces of the mechanical invaders rained down into the ocean below, their forces decimated in mere moments. Within minutes, the once-overwhelming army was reduced to scattered remnants.

Japan's Megafloats operators and commanders watching from the feeds barely had time to process what was happening.

As they were left stunned and speechless, the machine turned its attention to the invaders' huge mothership that easily exceeded 20 meters in length, and the remnants of the AU army scrambled in vain to defend their flagship.

Such was an impossible sight, since it was well known just how resilient their construct was.

Yet, the machine didn't seem to be quite finished yet.

"Attack Function."

The machine suddenly said as its bladed wings unfurled with an audible shing, and green energy began to coalesce around its core.

TSUM!

A low hum reverberated as the machine's cannon fully charged. As it did, a green-like halo appeared behind the machine.

For a brief, surreal moment, everyone watching through the satellite feed heard it.

…. For the first time, they heard a human-like mechanical voice.

"Disappeared to dust."

With that command, the fully charged cannon shot forward towards the mothership of the invading army.

BOOM!

A loud explosion that could rival that of an atomic explosion or even greater resounded.

The remnants of the AU army, as well as the mothership, were eviscerated from existence.

Then, just as it came—

Behind the large machine, once more, the deep-blue diamond-like portal appeared as the machine flew into it.

Naturally, the sudden appearance of such a different and powerful machine plunged not only Japan's Megafloat into chaos but also left the entire world's military forces in turmoil.

Every agency, intelligence bureau, and strategist across the globe scrambled to answer the same question:

Who owned such a machine?

⸻Meanwhile.

The machine's owner in question.

The very individual the world was desperately searching for wandered the streets of the Tactical Defence City, Ataraxia, completely unbothered.

[Master could have originally blocked out the peering signal but chose to let them be. Navi doesn't understand]

"Listen here, Navi. Things are much more interesting when you've got eyes on you."

[So, Master is an attention seeker?]

"Only when it demands."

Walking along the streets of the tactical defence city was a young boy no younger than the age of eighteen with brown hair and sharp features.

He had an identification card hung by his neck.

[Tactical Defence City—Ataraxia]

[Name]: Mitsuya Kimitsuki.

[Resident]

Today was the day he's moving from Tokyo's Megafloat to Ataraxia.

But on his way here, Navi had noticed the AU army and had alerted him.

With the machine «Dimension Cross»—a weapon from his previous world he reincarnated into—he drove them back without breaking a sweat.

Not that anyone would guess—Mitsuya's nonchalant attitude gave no indication of his involvement.

Accompany him was the «Dimension Cross Main System: Navi».

"By the way, where's our place?"

The «Dimension Cross Main System» is more advanced—and by more, meant leaps and bounds more advanced than this world's technology.

It uses quantum computing to operate itself, both the «main system: Navi» and the machine itself.

Mitsuya on the other hand, to some extent could also manipulate a quantum territory—requirements for piloting the machine—though, at best, he could only manipulate Fundamental Forces in a certain area around him.

But aside. Because of their advanced prowess, hacking a few systems even with this world's technological progress is a piece of cake.

[Yes. Master's quarters is by district 8 of the Tactical Defence City Ataraxia]

"Roger that."

He said as he walked two steps forward before looking around.

Small-type electric automobiles were coming and going through the main streets with students and residents walking through the road.

Digital synergies floating in the air were lining up along the sidewalk. Advertisements of products and news and the like were projected on them.

These things would supposedly also get used in an emergency for urgent information and evacuation instructions.

At both sides of the sidewalk, shopping malls and cafés, brand shops, etc., various shops were standing in a row.

Then… At the plaza of the shopping mall, there was an amateur band doing a launching concert.

Near that, there was also a game centre. There, some guys were playing games while holding bentos in one hand.

In outline, this place should be a military facility, but… in reality, this place was really full of freedom.

"But still. This world isn't bad at all."

Mitsuya laughed.

[Master can travel to another world right now if he so wishes. The Dimensional Gateway can be opened anytime now. It is no issue]

Mitsuya nodded but then shook his head with a small smile.

"It won't be fun otherwise. At least, let me enjoy life here first before moving to another world."

On that note, since his machine operates on a quantum level, even something like opening a dimension gate can be done.

Since a machine like Cross operates on that level, energy consumption is the least of their worries. However, the problem would be on Mitsuya since the burden of using the machine is on him.

Hence, he couldn't willy-nilly cross worlds on a whim.

"By the way, can you recreate something like the «Hybrid Gear» for me? I'm thinking of enjoying a little bit of Academy life."

[Understood. While the materials available in the Quantum Space are limited, they should suffice to construct something similar to a «Hybrid Gear» for Master. How would you like the gear to be configured?]

"Hm, a sword and a miniature device—one that can assist with calculations when I'm using «Territory»… like How DC's assist terminal helps me when piloting Cross."

"I'll design the structure of the gear when we get to my place; it will be called «Mythos»"

[The sword should be straightforward to create. However, the device may require considerable trial, error, and testing]

"That's fine by me."

Mitsuya said so as they passed a gyudon shop. Everywhere was packed with people.

Furthermore, from the looks of it, ninety percent of the customers were wearing Ataraxia's uniform.

Taking a pause, Mitsuya then asked for the «DC Main System»—the mini version—installed on his smartphone.

"By the way, check Japan's record for a name called Hida Kizuna and anything concerning him."

[Understood.]

The AI replied as it began working.

At the very least, this search would confirm which point in time he had landed in.

If he isn't on Ataraxia, then that means the plot hasn't started.

Then depending on what he finds out from the «DC Main System», he should be able to estimate the current timeline.

A subtle smile tugged at the corners of his lips as he thought.

'Since I'll need a variety of materials for future constructions, I also need to explore this world.'

After all, this is his grand goal.

But for now.

Reaching his resident quarters will suffice for now.