"Sir, we have intercepted a message from the Destroyer Harekaze to the Submarine I-201 from Toumai High."

"What does it say."

"It says, 'We are from the Yokosuka Girls' Marine High School. Destroyer Ship Harekaze. We have no intention of fighting.' That was what the message roughly conveyed, sir."

"So they have no intention of fighting, huh? Is this the same ship that mutinied and sank the Sarushima? Was the captive mistaken for this information"

"Most likely not, sir. Chief Signal Officer, who had intercepted the message, says that the Harekaze used active sonar on the I-201 as well as the message was based on the same method."

"...They're amateurs, aren't they?" the man remarked rather sarcastically.

Who in the right mind would use active sonar to contact a submarine peacefully!? That's equivalent to declaring war on a goddamn country!

If you're a competent Sonar Technician or Operator in a Destroyer, you shouldn't be doing that, literally.

Submarines never use active sonar even though they have it. Being a sub means being hidden - it also comes a catchy motto "We listen, but we don't talk" - and using active means giving their position to the world. If a sub uses active, just a few pings and they are about to fire.

From a tactical viewpoint of using active sonar for a Destroyer-gone-renegade. Active gives you a much more precise picture that you will need if you want to deliberately fire on something. Active was only used to get an accurate range for a firing solution.

However, in a boat-on-boat situation that one ping says, "I've found you, you're in my sights and now I have a very accurate firing solution."

This would end in a grave misunderstanding.

A misunderstanding they would use to exploit to its fullest.

"Anything else that we might've missed?"

"They've damaged the Graf Spee before the Submarine I-201's encounter, sir."

"Anything else other than that?"

"One of the twenty captives is a former member of the Blue Mermaids now sailor for an Instructor Ship, and one of the twenty people who were on board the Sarushima that we've captured."

"Other than that?"

"That we have currently 688 ships, some of which were obsolete Destroyers that have been assigned to a secondary role(?)."

The man in charge gave out an exasperated sigh, "It's been eight days. Eight days on sea, since the entire Combined Fleet had been transported to this world. Twice we've been transported to another world. Isolated and under strict orders of the Admiral who was somehow transported along with us. Sank a goddamn Destroyer ship that looks suspiciously too much American for my taste. And now, a sailor in front of me has been infected by some sort of stupidity-induced disease of this world." he silently said, mostly to himself.

After they had defeated the oh-so barbaric kingdom that threatened to conquer the Principality and neighboring Kingdom that the Empire of Japan had so conveniently made several trade deals with.

Like before, it all had happened so suddenly.

"What should we do now, sir?"

"For now, observe. After they have handled Toumai's Submarine, we sink that sub afterward with all hands. The instructor of Toumai High will contact the so-called Blue Mermaids and they would likely put the blame the sinking towards the Harekaze. After that, contact Task Force I-400, under the command of Rear-Admiral Misaki Akito, they should be waiting to intercept the Harekaze from their predicted escape route."

"Yes, Rear-Admiral Munetani Yamashiro, sir!"

Earlier.

The Imperial Japanese Navy, or IJN for short, was arguably the strongest naval force in the New World.

With only 24 ships (13 Destroyers, 6 Light Cruisers, and 5 Battleships) had won a naval battle against the 4,400 obsolete sail-ships of the medieval era and a large air wing of 150 Wyverns - that can reach a maximum speed of 230 km/h - in the Great Battle of the Rodenius Sea.

That naval battle will later be described as more of a massacre rather than a "battle".

Having sunk 4,200 ships out of 4,400; annihilating all 150 flying creatures of fantasy without a single casualty from the 24-ship Task Force that was sent to intercept the combined fleet. It was a decisive battle.

A decisive battle of epic proportions that most of the senior flag officers of the Imperial Navy had dreamed longingly since their decisive victory in the Battle of Tsushima against the Imperial Russian Navy during the Russo-Japanese War.

Having much more control over the enemy's territorial waters, they were wreaking havoc on their enemy as they made a major naval blockade on the coast of a nation that was one-fourth the size of Australia. Effectively cutting them off from any shipping lanes and sinking of any that dared to have raised the flag of their enemy.

However, on the 5th Month and 1st Day of the natives' Central Calendar of the Year 1639 - the Gregorian Calender equivalent would May 1st, 1948 - a mysterious phenomenon had occurred.

They had, once again, been transported to another world.

But this time, the Imperial Navy was the ones that had been transported.

The bulk that made up the IJN had ended up in this entirely new world, Admiral Yamamoto Isoroku, Commander-in-Chief of the entire Combined Fleet, had ordered all submarines under his command that had transported with them to survey the seas of this world.

They all complied with his orders.

One of the submarines that were sent to scour the seas was the Submarine Aircraft Carrier, I-400.

The I-400 was the lead ship of the I-400-class Submarines that were the submarines the world has ever seen. Far larger than their Axis allies, as well as their enemies' submarines, could ever compare.

Boasting a maximum range that allows them to travel around the world one and a half times, they were the brainchild of the same Admiral that had led the IJN as their Commander-in-Chief.

Aside from their overall size, they are capable of housing three Torpedo-Dive Bomber Floatplanes each. They were designed to launch these same aircraft to any Allied nations in the world.

However, after experiencing the setbacks of having a large submarine, it would be impossible to have operated these large submarines during the Pacific War against the Western Giant.

It would have been deemed impossible if it weren't the timely, or in this case, sudden transfer to the New World.

With their Emperor issuing a five-year-long isolation policy, the Navy had enough time to address the glaring problems the I-400 Submarines have.

I-400-class subs were retrofitted with a wieldy and relatively easy to maneuver while surfaced, owing to their now-large rudders. They had adjusted the superstructure to prevent the sub to veer off course during any strong wind. The maximum safe diving depth of the I-400-class submarine was lowered by half of its tested depth, which allows the submarine to dive at not too steep an angle in an emergency.

Because of their large aircraft hangers and conning tower, all I-400-class subs had significant visual and radar signatures on the surface and could be detected by aircraft relatively easily.

To combat this, Naval Technicians introduced a special coating that was recently discovered in the New World that allowed the I-400-class to be invisible even the most advance radar Japan could produce to date.

The element used on the coating was appropriately called "Mithril".

Dive time was significantly improved to allow them to rival their US counterparts in terms of Diving speed, which made the boats easier to escape from the air when caught on the surface.

Even when submerged and traveling at an improved speed of six knots, the now-adjusted superstructure can allow the helmsman to easily steer a straight course with relative ease. When conducting a torpedo attack, the captain has an easier time to take into account compared when the subs had an offset design that would force the captain to take into account his larger turning circle to starboard than to port.

During the isolation policy, submarines in the Imperial Navy were installed with air-conditioning to control temperatures in tropic waters, which also includes flush toilets that the crew sailing in these submersible sea vessels were extremely grateful for.

They have installed cold storage for food that greatly improves the crew's diet while adding adequate sleeping quarters that made some of the crew more grateful as they won't have to sleep on the decks or in passageways inside the sub.

It was these significant improvements that allowed the I-400-class Submarines a more formidable force to be reckoned with.

Fortunately, it was these advantages that allowed them to capture twenty sailors of the sinking Sarushima that they were able to gain information of strategic importance for the Imperial Navy.

Now armed with the knowledge gain from the twenty captives, the Combined Fleet under Admiral Yamamoto will take this world by storm.

Now, there were two important questions.

One, how would they go back?

Second, does this world's Japan still has the Emperor?

IJN Composition: 700+ ships

Fleet Carriers: 22

Light Carriers: 8

Escort Carriers: 12

Seaplane Tenders: 12

Fast Battleships: 4

Battleships: 11

Heavy Cruisers: 18

Light Cruisers: 28

Destroyers: 377

Submarines: 196 (All of them are I-class Submarines)

Total Carrier Aircraft: 1,803

Seaplanes: 109

Hello, everyone, this is gabrielchiong11, and this my first story in this community.

As anyone who might be reading this, there are some things that I need to address.

The IJN in this fic are not from our Timeline but they're from my other story *insert shameless advertising* so please read it!

If you like this story, be sure to press the fav and follow button. Be sure to leave a review as well.

That is all, gabrielchiong11, out!

Be safe from the virus everyone.