a/n: This is a new story that I have been rolling around in my mind for a while. I don't know how often I will update it after this, or if I will at all. It all depends on whether or not you like it. This is based on the Manga version of Aoki Hagane no Arpeggio, which is really a completely different universe to the anime. If you are here for the Konosuba portion of the story and have not read Aoki Hagane, I highly recommend it, as it is a masterpiece.

Chapter 1 - The Future is (not) Bright

"Can you stand?"

The voice belonged to a young man of about 17, though his black suit and tie radiated an air of maturity and utter confidence, which felt as if it shouldn't have been possible for someone of his age. His voice was soft but firm, and it dared anybody to challenge him.

"You have reached a dead-end 'Route Holder,'."

A second voice caused him to look up, and he let the woman in his arms down as his opposition continued.

"Or should I call you 'Battleship Killer?'."

They were standing on a large expanse of smooth concrete, which was surrounded on 3 sides by deep water. It was a harbour. The night was cloudless, which enabled the moon to cast an eerie glow on both men's faces.

Despite similarities in their confidence, the difference between the two would be instantly apparent to any onlooker. The first man had his back to the angry ocean, while the other was backed by a small army. 50 men, all armed with lethal automatic weapons were taking aim.

"This entire area is locked down. Not even someone like you can escape if you jump into the ocean. We need that girl… for persuasion purposes, so we can't let you take her. Surely a genius such as you can see your only way out."

The girl in question was shaking with fear.

The second person grinned evilly. "How about it? Would you like to join us? We could use someone with your experience and intelligence in our ranks…"

Gunzou didn't say a word, but simply responded with a pleasant smile.

The grin on the second man's face vanished and transformed into a snarl.

"It's too bad…" He prepared to give the order to his men. "Battleship Killer."

With no warning but a silent swell in the water behind Gunzou, a silvery blade flew out of the ocean next to the pier. At the height of its leap, it slowed, and began falling. The people opposing Gunzou dropped their weapons and fled in terror at the sight that greeted them. The giant object made impact, and split the concrete pier in two, while sending large chunks of discarded material in all directions. Where there was once a solid concrete block, water was rushing in with vengeance around the object.

If someone were to take a birds-eye picture of this scene, they would see a 150-metre long war submarine, with its forward half cutting through an obliterated harbour platform.

A single torpedo ejected from one of its forward tubes and flew far enough before detonating to scatter the remaining enemies.

And then there was silence.

Once the dust had settled, another girl leapt off the deck of the submarine. It was some 10 metres up, and should have been an impossible jump, but she made it easily, landing softly on some intact concrete in front of Gunzou.

She appeared very young - 16 at most, but she carried herself with an importance that bordered on arrogance. Her waist-long hair was straight and white, and her fringe almost covered her eyes.

When she landed, she looked Gunzou right in the eyes.

"We looked all over for you," she said professionally, though her tone betrayed annoyance.

Gunzou smiled warmly. "Sorry, it's a long story," he said, "I'll tell you about it later."

"I can't wait." The girl responded sarcastically to Gunzou's apology.

"Let's go. We've still got another job to do." He said.

"Yeah. The girl responded.

…

Off the coast of the space centre in Kashima city, a terrifying war machine cut its way through the grey water.

A barrage of more than twenty missiles thundered towards it, and the cruiser did not attempt to intercept. They detonated, and the resulting explosion would have been deafening to anybody nearby, and the mere shockwave enough to crumble buildings.

Despite this, the cruiser left the smoke cloud, completely unharmed.

One hundred metres below the surface, someone exclaimed their distress in the bridge of an Attack Submarine.

"A cruiser of the Fleet of Fog…" Kashihara Kyouhei sighed.

"All right." The captain spoke. "Let's go over the details of this job again. First mate, please explain."

"Of course, captain Chihaya." Oribe Sou said. "Our goal is the protection of an SSTO (a/n: single-stage to orbit craft) used for international communication. Right now, our client is fighting that light cruiser, which is bent on its destruction. Our job is to stop its advance, and sink it if possible."

"Iona, show the data," Gunzou said.

The white-haired girl from before began speaking.

"Our target's displacement is over 6000 tonnes, and it is equipped with wave-force armour. Its armaments include six 123mm graviton cannons on three active turrets, 12 torpedo tubes and many missile launchers. Its top speed is 60 knots. It cannot submerge. That is the Fog Cruiser Nagara."

The bridge was silent for a few seconds. It was broken by Kyouhei.

"This won't be easy… what are your orders Captain?"

Chihaya Gunzou sat down in his chair at the back of the room, thinking. A couple of minutes passed before he said anything.

"Nagara hasn't noticed us yet…" He finally said. "High tide will soon come to these waters, which will switch the current in our favour. We will switch to silent running, and take Nagara by surprise."

Suddenly, another young woman, by the name of Hozumi Shizuka, yelped from the left lateral of the room.

"Nagara is turning her bearing to 212. She might have noticed us!"

Kyohei laughed. "You were saying, Captain?"

"Plan B it is then," Gunzou sighed, "All hands to your battle stations."

Kyouhei jumped into his seat, which was down a small set of stairs, to the right of Gunzou, and Shizuka signalled that she was ready from the left side.

Gunzou wasted no time. "Insert normal torpedoes into tubes 1 through 4. Active decoys in tubes 5 and 6!"

A 'Roger' from Kyouhei confirmed that the order was complete.

"Sonar, status." The Captain Demanded.

Shizuka, with her headphones on, responded.

"Nagara is gaining speed! It is coming right at us."

From the sky, Nagara seemed to be moving far too fast for its size. It fired its own barrage, the missile tubes on the deck opening, and ejecting several oblong cylinders into the water.

The sonar operator of the I-401 attack submarine picked up on this instantly.

"Something hit the water! I heard 12 of them!"

Gunzou did not seem anything but calm, especially considering their situation.

"Fire tubes 5 and 6." He said, "Then insert a corrosive torpedo into 5."

From the front of the I-401 flew 2 torpedoes through the water. After a few seconds, they detonated, but rather than explosions, two perfect replicas of the 401 appeared through a cloud of dust. They were there for a few seconds before they were obliterated by the torpedoes that Nagara had fired earlier.

"Sonar Reception falling," Shizuka said. "Enemy torpedoes confirmed intercepted… wait! One contact is making its way towards us! Distance 250!"

"It's too late!" Gunzou yelled. "All hands brace for imminent impact!"

A tremor shook the I-401, more powerful than an earthquake, and the crew would have been thrown across the room had they not been tied down automatically to their seats.

Iona was the only one who remained unfazed. "Klein field down by 20%." She reported, utterly calm, unlike Shizuka, who reported, almost panicking:

"12 more contacts incoming! This time there are Thanatonium readings; at least one of them is corrosive!"

Even Gunzou tensed at this report.

"Aim tubes one through 4 at the new barrage. Fire them in a salvo, with half a second between each one. Don't let the Corrosive torpedo through! Wait 10 seconds, then fire tube 5 at Nagara." Gunzou ordered, his calm complexion wavering.

On the surface, a plume of water, hundreds of metres high, was visible at the point where 16 high explosives detonated at once.

"All enemy contacts intercepted," Shizuka reported, relieved.

"Don't let your guard down!" Gunzou insisted. "Tube 5! The corrosive torpedo! Fire!"

A single shot came from the front of the I-401.

Nagara, one second, was cruising smoothly, and the next, it was listing horrifically to one side. Where the Corrosive Torpedo made an impact, a perfect sphere of purple light expanded, reaching 20 metres in diameter. At the epitome of its growth, it de-stabilized, and fizzled down in a spectacular display of purple lightning, leaving a perfect sphere gouged out of Nagara's hull.

5 kilometres away, on land, Kamikage Ryuujirou watched the resulting explosion through a pair of binoculars. "Great…" He muttered to himself. "The one who betrayed the fog… excellent performance."

Behind him, a small rocket launched. An SSTO. It sailed far into the sky, until it could no longer be seen, finalizing 401's mission.

…

In the early 21st century, due to a sudden rise in sea levels, humanity lost most of its terrestrial territory. Then, seemingly in response to these events, the previously unidentified 'Fleet of Fog' appeared.

Humanity was driven out of the seas by these mysterious battleships, which boasted overwhelming firepower, and nigh-unbreakable shields. Even humanity's most potent weapons, such as Hydrogen Bombs, proved to be unable to deal any significant damage.

Every continent and island was cut off from one another, and as a result, civilisation and prosperity took a big step back.

It had been 17 years since the final defeat of humanity at the hands of the fleet of fog.

But things were about to change.

…

"No, I don't know how we got here! Why don't you tell me!?" A voice in black space called out arrogantly.

"As I have already told you, I also have no idea, Kazuma. Can you please get away from me? Your presence is alarming."

"Hah? How can you even see me?"

"I can't, but I can sense your lewd thoughts."

"What kind of lewd thoughts are you having Kazuma!? Please elaborate!" This voice was a new one, and it seemed excited.

"Please don't… didn't I tell you to remove yourself from my immediate presence Kazuma? You are creeping me out."

"That's not me!"

"Ah yes, your voice is a little further away than it was before. These lewd thoughts must belong to Lalatina-sama. I apologise for my misunderstanding."

And then silence.

"Hey, don't you think Aqua has been silent for too long?"

"Yes."

"I agree."

"..."

"Haha! YOU GOT ME!" A third voice showed itself.

"How did you get up there?" The boy asked.

"What do you mean!? I am a goddess?"

And suddenly there was light.

And what was visible in the light? It was a flat expanse of what seemed to be clouds that went on as far as the eye could see.

"Seriously Aqua, that looks like fun. How did you get up there?" A girl with black hair and red eyes said.

"I told you already! I'm a goddess! It seems you can finally tell them the truth Kazuma!"

The boy, seemingly named Kazuma, looked into the sky, bored.

"What truth?"

"What do you mean 'what truth!?' You know the truth! I sent you to that world in the first place!"

This time, it was the red-eyed girl who responded.

"Well, send us back, please. I haven't used explosion today yet."

Aqua, a blue-haired girl, descended, close to tears.

The Quartet continued to argue and was only interrupted a few minutes later by a giggle.

"You four are so funny to watch."

"Eris-sama!"

The girl in yellow armour threw herself to her knees in respect, pulling Aqua down with her.

"Yo, Eris," Kazuma said.

Darkness, the girl in yellow armour, attacked him, but stopped in surprise when 'Eris' replied with:

"Hello there, Assistant-kun."

Two of the other three stared in surprise at Kazuma as he initiated a conversation with her.

"Say, do you know what happened to us? Why are we here?"

Eris smiled. "Of course. It-"

"-And why was I not told!?" Aqua interrupted.

"We couldn't contact you, because your godly form temporarily vanished when you descended to Belzerg," Eris responded, unfazed.

She turned to Kazuma.

"There is another world in danger, and the higher-ups have selected your party to help them out. What do you say?"

Kazuma took a deep breath and smiled. He looked lovingly to the red-eyed girl, Megumin, at his side, who smiled back. He looked to each of his party members in turn, still smiling. They all slowly nodded at him, and he shrugged his shoulders knowingly.

"Hell no." He said.

"Thank you for your help," Eris said. "I will now teleport you to- wait for what?"

Kazuma began to act violently. Had there been something to throw, he would have thrown it.

"There is no way in Hell that I am risking my life as a beginner in another world! I just started to enjoy my life in Belzerg! And, what of Belzerg!? What is going to happen to that world Hah?"

"Ah, well, the higher-ups decided that your party was best suited, as you are the strongest reincarnated that is doing almost nothing to defeat the devil king at the present time…"

Kazuma calmed down.

"Actually, that seems about right. So what's in it for us?"

Eris sighed. "You will be able to have one wish you succeed. Any wish. And this time, your goal is not to break the world out of their situation but to do what you can to help. You and your party will be the only ones incarnated."

"And we aren't dead?" Kazuma pressed.

"You are not."

"What will happen if we die in that world?"

"You and your party will be able to decide whether to reincarnate into Japan or Belzerg, at your choice."

"Any catches?"

"Err. If you choose to reincarnate into Belzerg, your level will be reset to zero."

"Let's go Kazuma!" Megumin interrupted excitedly.

"Why are you so eager?"

"I want to blow up new monsters! Also, if my level is reset to Zero when we return, I will gain skill points far faster than I would normally, which means I can increase my explosive destruction faster!"

Eris sighed again. "That would be correct. Your levels will be reset to zero upon reincarnating back to Belzerg, but your skills would remain."

Everyone fell into silence again, which Eris broke.

"There is no need to think so hard about it. You don't have a choice; it has already been decided."

"!"

Eris waved her hand. "Sorry, but I have to send you on your way, or my superiors will get mad. Bye!"

Golden light enveloped Kazuma, Darkness, Aqua (who was yelling hysterically), and Megumin.

Their surroundings went black once again.

"Hey, Kazuma, get away from me."

"Shut up, never mind that. Doesn't it seem pretty cold suddenly?"

"Yes, you are right."

"Ouch!"

Everyone ignored Aqua and the dull thunk of a person running into a metal wall.

"Wait a second, this is not magical darkness, it's just darkness." Kazuma's voice said. "Farsight."

The room lit up green in his vision after he used the 'Archer' class skill.

"Wait for a second, Aqua, you can see in complete darkness, how did you manage to walk into a wall?"

"Sh-shut up!" She respond, flustered.

"Oh, hey, I found a light switch," Kazuma said.

"Thank you, Kazuma." This was Darkness. "Nether Megumin nor I can see in this, as we do not have skills that enable us to."

"Yes, I got that Lalatina-sama."

"Please stop calling me that."

Around them was a room, in which everything seemed to be made of metal. There were boxes everywhere as if it were a storeroom, and the walls were slightly slanted outwards.

The room was thin for a storeroom, at only ten metres wide, but quite long; at least thirty five metres.

"Hah, what kind of fantasy world is this!?"

"Forgive me for pointing it out, Kazuma, but Eris-sama never said anything about fantasy." Darkness voiced.

"Oh, that is true, isn't it? Oh well. I was feeling a severe lack of Sci-fi recently, so this is actually good."

"Kazuma?" Megumin asked. "What is Sci-fi?"

Oh yes. This would be fun. Megumin came from a world in which she held the most powerful weapon. She would be in for a rough awakening if this universe was even semi-powerful.

Suddenly, the room's white lights went out, and they were replaced by blue. A young girls voice was easily audible above the rumbling that was occurring around us.

"I-401 Attack Submarine is now switching to combat mode. Please secure all un-grounded personal possessions, and move yourself to a safe location. Oxygen filters, High-power lights, and Life-Support systems are being disabled everywhere but the bridge and engine room in order to conserve power for the battle systems. All personnel, please move to a safe location. Repeat, please move to a safe location."

End of Chapter 1

Authors note: Well, I hope you enjoyed that. I do love this manga, and it deserves more love than it gets. By the way, I will continue uploading my other Crossover, so don't worry about that. I am going to write this Fanfiction part by part, when I have time, and upload when it when each chapter is ready, so it might be a while until the next one. This week I will not upload to my other Konosuba crossover; I will resume uploading that next week.