The evening sun had set half an hour ago, and the island in the middle of the ocean was shrouded in darkness as a few orange rays of sunlight still shone through the night and peeked over the horizon.
They barely illuminated the highest point of an island that was silently sitting in the midst of the dark ocean in almost meditative silence as its world was plunged into darkness once again.
The reason for said silence was the simple fact that mankind had never settled on the island that was located in the middle of nowhere, and didn't bear the trademark signs of human civilization like small plumes of smoke or artificial light sources that glowed in the midst of the forest like the luminescent tails of fireflies to keep the darkness at bay.
The forest was devoid of mankind's influence, and yet bore the usual signs of occupation that were dirt paths leading into the forest as a result of people trampling on the grass to go somewhere inland as well as disturbances in the lay of the land.
There were also several trees cut down to create a large clearing in the middle of the island, the dead trees reclaimed by nature as the trees were occupied by wildlife and flora with bugs and plants infesting the fallen tree barks, the wildlife on the island relatively unaffected and unconcerned about the war going between the metal-fleshed humans and the unnatural aliens that came from the sea.
This quiet and dark island was what greeted the Infiltration Fleet, this not being the first time laying their eyes upon this little island located out in the Pacific Ocean and slightly beyond the Safety Zone that divided ship girl territory from Abyssal infested waters.
Sendai and company had sneaked in when the sun had set after taking the entire morning and afternoon to confirm the Abyssal patrol routes and evade them, timing their entrance to coincide with a swap in Abyssal patrol fleets, all six of the ship girls wearing black to minimize the risk of an Abyssal spotting their flashy uniforms in the middle of the night as well as using their night-vision ability available to them as ship girls to navigate in the darkness, their world now a grainy green.
The Infiltration Fleet had already taken off their boat slippers as they approached the island, unable to use their ocean-based footwear to walk on land and leaving the job of maintenance to the Fairies who watched over their battle backpacks and boat slippers.
Chitose had already split up to hike up the hill located near the southeast section of the island to keep an eye on the surrounding ocean with the enhanced ocular organs that carriers possessed lest the Abyssals decide to change up their patrol routes and sail towards them, while Goya was patrolling the surrounding ocean for the exact same reason.
Sendai, Shiranui, Kagerou and Arare were patrolling the island while armed with two handheld 12 cm Single Gun Cannons each, the only weapons in their arsenal that were small and light enough to be wielded on land with minimum penalties to their movement speed, and some form of protection was better than none at all.
They were working on setting up the top-secret equipment that was loaned to them to be field-tested, Sendai having carried the five steel pikes that were wrapped in a blanket and tied with a black rope to secure it against the elements as Shiranui and Kagerou carried two shovels each to make their jobs easier.
Kirishima had explained to them that these pikes were designed to cancel out radio waves within the area that they covered and prevent radar from detecting their presence.
But they needed to see how large of an area the pikes could cover before the machine was unable to function, taking into account the shifting terrain that was the island it had to cover and the effectiveness of the radar-blocking pikes when going up against Abyssal radar.
And after an hour and a half of hiking, hard work digging up sand on the shores of the island to cover a large enough area and planting the spear-like machinery, the pikes were now ready to cancel out all radio waves and disallow radar from detecting the island to hide their presence on the island.
But activation would have to wait, as Kirishima had predicted that if they activated the pikes to block out all radio waves, it would include the radar of the ship girls on the island. Their search would be far harder if they couldn't split up to search the entire island while keeping in contact with each other.
The search was tedious, the Coordinators having predicted that they would have at least six hours after sunset to search the entire island before the Abyssals arrived, to which they'd detect the abnormality on the island and decide to check.
The four of them were determined to search the entire island, which thankfully wasn't that large as it was only four acres in terms of area, the ship girls starting with the artificial clearing in the middle of the island as the ship girls looked around to find the myriad of strangely-shaped rocks that was not the work of any human or ship girl.
They split up the clearing into a grid, whereupon the four ship girls would search the four sections of the clearing to make sure they didn't miss anything as they inspected the various rock formations to see if they contained some sort of well-kept secret, Sendai even smashing one rock with her steel fist to make sure that the relatively brittle granite wasn't hiding Abyssal steel.
That was an hour ago.
A sweating Arare, who was carrying the sling-bag that carried the syringe and their infiltration equipment to access and recover lost Abyssal data, perked up as she saw some sort of strange symbol being produced upon sitting down at the edge of the clearing, blinking as she stared at the entire rock formation that was sitting out in the clearing.
She leaned and tilted her head sideways as she shifted her body to crawl on all fours, observing how the rocks were placed in the clearing, all of different shapes and heights.
They ranged from destroyer-height to coming up short of knee-height, but there was one thing that the Asashio-Class destroyer could see from her point of view.
These rocks weren't supposed to be here, despite how innocuous they looked.
And now that she had positioned herself well enough, she called her teammates over as she pointed out.
"These rocks look like they're leading somewhere."
And Kagerou voiced out a disbelieving,
"Eh, are you sure? Could it be the Abyssals trying to mislead us or something?"
But Sendai respectfully disagreed, citing the strange sight that beheld them as they approached the island.
"No, man, I don't think that's the case. Remember all the boulders that the Abyssals brought onto this island back when the Abyssal War started, some of which we came across and looked pretty obvious someone hauled 'em here? And don't you think these rocks are markers, as we see here..."
The Infiltration Fleet looked forward, seeing that the rock formation of varying heights and seemingly scattered randomly throughout the clearing lined up almost perfectly from their point of view to form an iron sight of sorts, with the stones forming a "U" with a short rock jutting out in the middle.
"... And might be arranged to indicate a direction to travel in? I mean, I might be wrong, but remember that this pointed in the general direction of one of the boulders located in my section."
Kagerou shrugged in response, while Shiranui added her own opinion on things.
"I think that everything here's just a diversion. They wouldn't be so stupid as to hide what they're up to here in plain sight since this's the first place we would start looking, and I think that the few boulders we've seen here are markers, to hide one amongst many. And besides..."
Pointing to the rocks that didn't completely line up with the formation, Shiranui noted.
"I think there're a few false markers to mislead us, as looking at this formation from different angles would give different results. We have to assume that the Abyssals wouldn't want us to find it, and would do their best to give us false leads, since it seems as though the formation points in different directions."
Walking around the formation, they saw that the formation of the rocks were shaped in such a way that allowed them to point in five different directions, the four of them convened to decide on whether they should split up or stay together to get things done faster.
But finally, Kagerou pointed something out as she thought about the formations.
"Y'know, I won't say that I'm 100% correct on this, but I'm here thinking if they would want to hide their secret in a location where it's closer to the Pacific Ocean where they come from?"
Everyone blinked at that, accepting that logic as they walked into the forest, doing their best not to disturb the wildlife as they trekked through the grass and trees and followed Kagerou as she sounded as if she had a point.
And after three minutes of brisk hiking, they found themselves facing a boulder sitting right in the middle of a distinctly smaller clearing, one of many strange monuments scattered throughout the island.
This boulder was the closest to the Pacific Ocean when compared to the four other boulders that the rock formation pointed to, but wasn't the closest to the shoreline when comparing it to the boulders littering the island, since a few boulders lined the beaches and effectively hid it amongst other dummy boulder markers.
Sendai and the girls got to work in moving the average-sized boulder, selected likely because of its portability and the weight it possessed, the Infiltration Fleet easily able to achieve a heavy cruiser's level of super-strength when they all turned their ship girl modes on as the boulder was finally moved aside, the girls getting to work on digging a hole to uncover whatever lay beneath the boulder.
The Coordinators had told them that the shovels that they brought served two purposes, where one was to dig into the beach to install the radio wave-jamming pikes, and the second was to uncover any potential Abyssal secret hidden underground, since if a cursory search of the island surface yielded no results, where else could they go but down?
And fifteen minutes of sweat-filled excavating with the speechless and slightly imposing boulder being a bystander as they had dug a deep and wide pit where the boulder once set and getting their uniforms dirty, Kagerou's drudging shovel hit something hard, the hard and sharp echo of metal upon metal ringing throughout the site, silencing the ship girls present and causing them to freeze up upon hearing that.
Sendai and Kagerou discarded their shovels and immediately dropped on all fours to push the dirt out of the way, while Shiranui and Arare, both of them resting up to prevent exhaustion before the sortie that was to come later, joined them in the pit and mimicked their motions to clear the dirt from steel.
Uncovering some sort of steel hatch that was now dulled, the four ship girls gazed upon a symbol imprinted into the dark steel, a stylized capital "A" designed to look like a shark swimming towards the surface ala Jaws , complete with small yet sharp teeth and small beady semicircles to symbolize shark eyes.
This was the rarely-seen Abyssal symbol used by the underwater invaders, and much like the Imperial Chrysanthemum was to the Japanese, whatever was stored beneath this hatch was undoubtedly Abyssal property.
Jackpot.