*Arcana Sanctum 

*Evan/My POV

We were sailing around the Arcana Sanctum when we saw Siren Ships in the distance. 

"Careful, a Siren guard fleet has appeared." Gremyashchy alerted us.  

"Seriously? We cleaned out this place not that long ago..." Murmansk protested. 

"Those look like some seriously outdated models." I remarked. 

"The enemy models in the Arcana Sanctum have never been upgraded. They're the exact same as they first were when this place was discovered decades ago. Let's end this quickly! Uraaa!" Kirov shouted her battlecry before engaging the sirens with the rest of the Northern Parliament shipgirls. 

"Lady Forbin, Le Triomphant. Engage." I commanded. 

"Come on Le Triomphant." Lady Forbin urged before both of them jumped into the sea. 

*Third Person POV 

Belorussiya fired a salvo at the siren ships, sinking some of them while the other Northern Parliament shipgirls charged forward to try and score some torpedo hits. 

"Vperod!" Murmansk fired her torpedoes before quickly retreating. Unfortunately, all of the torpedoes missed. 

"Take this! Unity is strength!" Gromky fired her torpedoes, sinking some of the siren ships in the process. 

"Out of the way." Gremyashchy fired her torpedoes and like Gromky, managed to sink some of the siren ships in the process. 

"Fire all cannons! Don't stop shooting!" Tallinn fired her guns and torpedoes at the siren ships, hitting and sinking some of them. 

"Kirov reporting!" Kirov fired her torpedoes. 

Le Triomphant and Forbin entered the battle and finished off the remaining siren ships. 

"Amazing sword fighting Comrades." Belorussiya commented.

The fleet made its way to a massive iceberg, easily dispatching the enemies in the way. It is said that this iceberg is the only facility here with an internal structure, and also houses the "Gate." 

"This place is where we first recovered some truly revolutionary information. Isn't it spectacular, Comrade? The first time, we had to fight our way here. Countless comrades became martyrs in these very waters before we finally managed to clear out the swarming Siren forces. But considering what we got out of it... their sacrifices were not in vain." Kirov remarked.

"It can be said that what we discovered here was a turning point for fate. The intelligence we recovered from here was the reason why the Northern Parliament, then on the verge of collapse, managed to hold its tattered line of defense and then claw its way back into becoming one of the major world powers today. But that's not all. We also discovered a sliver of the Sirens' secrets..." Belorussiya pointed out. 

"The Sirens' secrets...?" Evan asked. 

"What I'm about to tell you has never been made public. After so much information has been leaked, we've completely lost trust in the ability of the Naval HQ to maintain confidentiality, but we do think you need to know this information." Belorussiya replied. 

"I'm guessing that I need to keep this a secret from the Naval HQ?" Evan asked. 

"That's not our intent, no. However, I do hope that after listening to everything, you will utilize your best judgment in deciding what to disclose. All the information you learn in the Arcana Sanctum today should be treated in that manner." Belorussiya replied. 

"Okay" Evan replied. 

"We're almost convinced that the Sirens were not spontaneously "born" from these oceans, in any sense of the word, but rather came from a distant place. As for their true purpose, it is not something as simple as trying to eradicate humanity. Since the very beginning, most of their actions have been aimed at driving wedges between our major factions and amplifying those conflicts, plunging us into a state of endless war. Looking back at everything that's happened, the Iron Blood had the deepest ties to the Sirens. Their splintering from the Azur Lane, sudden betrayal, and formation of the Crimson Axis, all reek with the Sirens' lingering influence. And perhaps, us too in the past, no... Even right now, we might have walked straight into a trap set by the Sirens." Belorussiya explained. 

"It's not just you. Both the Eagle Union and Royal Navy have been somewhat aware of this." Evan commented. 

"Somewhat aware, perhaps. But they still continued to fight, whatever the reasons may have been. In the end, everything still happened as the Sirens desired. This is the true nature of their power. As for where the Sirens came from and what they're actually after... Unfortunately, we still haven't found the answers. But we're sure that the answers can be found behind the Gate. We'll reach it on the other side of this great hall. Let's keep moving." Belorussiya explained further before instructing everyone to move. 

*Timeskip 

*Evan/My POV 

"So, the reason you need me is because you haven't been able to open the Gate." I said. 

"Correct. We believe that your natural attunement to Wisdom Cubes will aid us in opening this dusty Gate. We've scoured the entire Mirror Sea, but have not found any device that can control the facilities here. We can't even control the Mirror Sea or access its maintenance device. The most suspicious thing is this console up in front." Kirov replied before pointing to a metallic console that looks like some kind of control device in the middle of the great hall. 

"There's a groove in it where you're supposed to insert a Wisdom Cube, right?" Tallinn asked. 

"Seems like it... It does look like some special device that requires a Wisdom Cube to activate. However, all the Siren devices and facilities we've encountered so far have been powered by a special energy storage device. Why would this thing here require a Wisdom Cube to activate?" I asked. 

"We may never know until we see what's on the other side of this door." Belorussiya replied. 

"We've conducted a series of experiments to try to activate the console, but everything we've tried has resulted in failure. It won't respond at all." Tallinn added in. 

"So you believe that this device will only respond to special individuals?" I asked. 

"The tests you took when you first became a commander showed that you have the highest attunement with Wisdom Cubes that this world has ever seen. All the science we have today cannot explain why you are able to produce benign changes to Wisdom Cubes, but even you should be aware of this phenomenon." Kirov replied. 

"Why me? And where is this "Gate" that you keep talking about? We've reached the end of the great hall, but I don't see any doors here..." I asked. 

"Sorry, sorry. I forgot to tell you one little detail about the Gate" Belorussiya apologized. 

"The wall of ice in front of you, right at the end of this hall, is what we call the "Gate." We're confident that if you're able to activate this console, this will open up into another passage." Belorussiya explained. 

"It's just a sheet of ice." I said. 

"And that's where you'd be wrong, Comrade. There's much, much more to it than that. Gromky, let's do a little demonstration for the commander. Shoot at that corner over there." Tallinn pointed at the ice wall. 

"Everyone, please keep a safe distance! Commencing fire!" Gromky fired her guns at the ice wall. The shell discharged from Gromky's gun slammed into the wall of ice and erupted in a cloud of smoke and steam... But when it cleared, there wasn't a scratch on the wall... 

"As you can see, we can't damage the wall even with this amount of force. Of course, we've tried many other methods. Using larger-caliber guns, having the entire fleet fire salvos, using explosives, using heavier explosives..." Tallinn explained. 

"How about swords?" Lady Forbin asked before smashing the ice wall with her Durandal. Even with her Durandal, there was no scratch on the ice wall. 

"Using giant swords even. But nothing has worked so far. All the firepower we've been able to muster to date, and still not a scratch on this wall." Tallinn finished explaining. 

"I guess you really do have to work from the console... Hm? Wait, this insignia here... it's not what the Sirens use to represent themselves... I've never seen this before." I pointed out. 

"I don't think we would've glossed over something like that..." Murmansk frowned. 

"What...?! Impossible! I'm certain that symbol was never there before." Tallinn exclaimed. 

"In other words, the console changed in a way we've never seen before? Sure enough, mysterious things start to happen as soon as the commander sets foot in here... Here, use this Wisdom Cube. Don't keep us waiting. Go ahead and give it a try." Belorussiya gave me a Wisdom Cube. As soon as I pressed the Wisdom Cube into the groove, the device began to vibrate and hum. The Wisdom Cube seemed to dissolve, replaced by a ball of light that expanded above the console.

"...Woah, the console's actually reacting!" Gremyashchy exclaimed. 

"Woaahhhh... It's glowing!" Gromky commented. 

"The structure of the Wisdom Cube is reflected in the motes of light... as if they're trying to deconstruct the cube..." Tallinn remarked.