Hakugei-class submarine

Hakugei class submarine 'wearing' an assault module

Hakugei class submarines are cutting-edge modular nuclear submarines developed in Japan in order to combat "Fleet of Fog". So far, only Hakugei (3) was shown, while it was mentioned that both Hakugei (1) and Hakugei (2) were sunk.

Hakugei class submarine

Not content with being pushed out of the seas by the "Fleet of Fog" Japan began creating weapons in order to combat this threat. Hakugei class submarines are one of these weapons. These state-of-art nuclear submarines are equipped with cutting-edge technology. Because of their modular design, Hakugei class submarines can vary in size from 100 to 1000 meters long. Modular design also allows for a quick re-purposing of the submarine and grants additional protection to the crew as damaged parts can easily be disconnected from the rest of the boat.

Supercavitation Propulsion Mode

Hakugei class submarines have several modes of underwater movement. In addition to standard propellers, there are also micromotion tiles that allow this mothership-size submarine to remain hidden even from the sensors of the "Fleet of Fog" vessels. Unfortunately, these micromotion tiles are rather fragile and strong shocks can render them unusable... Finally, Hakugei class submarines are equipped with supercavitation propulsion that allows the submarine to reach the speed of 110 knots while underwater - this makes Hakugei class submarine one of the fastest vessels in the "Aoki Hagane no Arpeggio" universe. However, the submarine can carry only so much rocket fuel and can support supercavitation propulsion mode for only around 30 seconds.

Hakugei class submarines, while using assault module, have eight frontal torpedo tubes and a number of anti-missile defense guns in the side ports. There are also underwater mine despensers hidden along the submarine's body - these are also used as a part of anti-missile defense system. It is possible that these submarines have other weapons, but those were never shown. It is also unknown, what weapons and in what quantities Hakugei class submarine has while using cruising module.

Hakugei (3) submarine

captain Komaki, commander of Hakugei (3) submarine

The only Hakugei class submarine shown is Hakugei (3) under the command of captain Komaki. This submarine is stationed in Yokosuka port and had her baptism of fire when the port was attacked by "Fog" battleships Haruna and Kirishima. During that time, Hakugei (3) was equipped with an assault module and was around 200 meters long.

It was immediately proven that micromotion tiles provide the submarine with the necessary level of stealth to get a drop on the "Fleet of Fog" vessels - Hakugei (3) was detected only when she was sending a radiogram. However, the immediate task of Hakugei (3) was creating a distraction in order for I-401 to get out of the bay and collect her crew, Hakugei (3) used her supercavitation propulsion in order to capture Haruna's and Kirishima's attention.

That worked, however, it soon left Hakugei (3), that isn't suited for soaking up large amounts of damage, alone against two "Fog" battleships. Captain Komaki decided that they should use Sound-Cluster torpedo in order to hide, but the modulating speakers that were supposed to create a curtain of sound to hide the submarine were quickly destoryed by battleship Kirishima. That very same attack also badly damaged the micromotion tiles of Hakugei (3) and temporary disabled a lot of her internal systems. However, the "Fleet of Fog" battleships failed to destroy the submarine as Hakugei's anti-missile defense guns kept it safe for long enough for I-401 to return onto the battlefield and draw Haruna's and Kirishima's attention away from Hakugei (3).

Later, during the final stage of the battle plan, Hakugei (3) used the Corrosive Warhead Torpedo given to them by I-401 earlier to destroy both Haruna and Kirishima while the battleships were joined together for their joint-mode Super-Graviton Cannon. That was the first time in history when a human-made vessel sunk a "Fog" battleship, even if the "Fog"-exclusive Corrosive Warhead Torpedo was used to achieve that.

While Hakugei (3) had sustained some significant damage during the battle, the command and the reactor modules survived with only minor damage. The badly damaged assault module was abandoned on the bottom of Yokosuka bay. Quite possibly it was recovered after the spatial distortion from the destruction of two "Fleet of Fog" battleships ceased.

Hakugei class submarine 'wearing' a cruising module

Hakugei class nuclear submarine (cruising module) and I-401

Hakugei (3) reappeared some time later, now equipped with a cruising module. Now she is a true mothership submarine, estimated to be around six hundreds meters in length and possibly even more in width when measured by her wing-span. The only question is how she was assembled like this as no docks are this big...

Even without those 'wings', Hakugei is at least eighty meters wide. This makes Hakugei (3) the largest vessel in the "Aoki Hagane no Arpeggio" universe. I-401, despite being 122 meters long, looks rather tiny when compared to this monstrous submarine.

The cruising module gives Hakugei (3) six docking points where smaller submarines can dock in order to resupply or - as it was the case with I-401 - to allow the crew to have a live meeting. For that purpose, there is a briefing hall available inboard of Hakugei (3).

After the general points of the trans-Pacific voyage for the two submarines were discussed, I-401 broke away from Hakugei (3) and headed to where Takao was fighting against U-2501. While I-401 failed to save Takao or retrieve her core, they learned that the 'tsundere heavy cruiser' had been resqued by I-402. Thus, having no reason to stay in those waters anymore, I-401 headed back to Hakugei (3) in order to continue (well, start) their journey across the ocean.

While waiting for I-401 to rendezvous with them again, Hakugei (3) witnessed an in-fighting between Repulse and a destroyer accompanying her against a group of the "Fleet of Fog" vessels led by Prince of Wales. After some debates, captain Komaki decided that they should assist the fleeting heavy cruiser to the best of their ability. To that end, Hakugei (3) fired a Sound-Cluster torpedo to provide Repulse with a window of opportunity to slip away from her pursuers. Then Hakugei (3) switched to silent mode and began descending in order to remain undetected by Prince of Wales's fleet.

Sometime Later Hakugei (3) randevoued with the Matsushima were it loaded the vibration warhead from the sub as well as recieving the plans for the device from Gonzou. Now entrusting to deliever the faith of humanity to both the submarine and it's crew