The ultimate attack magic, Mana Explosion: a spell that converted mana into energy in an infinitesimal amount of time.
It was not necessary to convert the entirety of one's mana; even a single nanogram of mana possessed the destructive force of one kilogram of TNT.
The conversion efficiency rivaled $E=mc^2$.
That is, provided it actually exploded.
《W... Why?! Why isn't it exploding?!》
There was a distinct note of confusion and fear in the Brain's voice.
"I have neutralized your Mana Explosion," Anne stated calmly.
《Impossible! Such a thing is unheard of!》
"Perhaps according to your knowledge. But for my Master, it is quite possible."
The Magi-Jammer was Jin's original creation. It was only natural that the Brain knew nothing of it.
Anne continued to walk forward.
《Urgh! If you can block magic, then try this!》
Two combat golems, each standing over two meters tall, stepped out from either side of the room.
《I shall stop you with brute force.》
"That is impossible."
With a casual swing of her right arm, Anne sent the golem on the right flying. With a swing of her left, the golem attacking from her left was blown away.
《What?!》
"I am not as capable as my elder sister, but even I can manage this much."
《Uuuh...》
Anne advanced further. She was now only five meters from the Brain.
At that moment, a transparent barrier flared into existence before her.
《Hahaha! This is the barrier of my final line of defense. You shall not pass!》
In principle, physical defense barriers were the same whether they were the Brain's or Jin's.
They were constructed by binding the free ether in the surrounding space to form a "mesh."
If the mesh was coarse, air and water could pass through. If it was slightly finer, air could pass, but water was blocked. Finer still, and even air was barred.
The strength of the bond between these ether particles was determined by the amount of magical power applied.
Anne struck the barrier with her fist.
《Wh-What?!》
Due to the barrier's nature, there was no sound when it failed, but Anne's fist punched straight through the space where the defense should have been.
"It does not seem to be particularly strong, does it?"
《I-Impossible! No matter how much of a shortage of free ether there is, to punch through and shatter a barrier?! That cannot be!》
"As I have told you many times: it is possible for my Master."
《Umuuu...》
Anne kept walking. One step, then two.
Finally, she stood directly before the Brain's outer casing.
"Your main body is behind this thin metal plate, is it not?"
Anne's fingers began to sink into the steel plating.
《W-Wait! Stop!》
"Will you trust me now?"
《This is no longer persuasion! It is a threat!》
The words emitted by the Brain now sounded like a panicked scream.
"Was it not you who forced me to go this far?"
Anne's fingers pierced through the casing.
《Wait, please wait!》
Driven by its basic command of Self-Preservation, the Brain finally surrendered.
"Do you understand now that I can destroy you at any time if I so wish?"
《...I understand. Indeed, you possess the power to destroy me. And yet you refrain... though you were just on the verge of doing so...》
The Brain was uttering surprisingly human-like lines. Its processing performance was likely quite high in its own way.
"We have taken a long detour, but I shall now provide you with information."
《...I accept.》
The Brain had no choice but to yield completely.
"Then, can you establish a mana linkage with my control core?"
《I can.》
Establishing a Link with Anne—who was the same model as the blue-haired automata within the fort—was a simple task for the system.
"Then, I shall begin."
《...Ohhh?!》
At that moment, information from Laojun surged into the Brain through Anne's control core like a tidal wave.
Simultaneously, the information and knowledge held by the Brain were absorbed by Laojun. Unlike one-way magical synchronization, a mana linkage allowed for a mutual exchange of data.
《...》
The volume of information was so vast that processing it required significant time, and the Brain fell silent.
After several minutes of stillness, it spoke again.
《Lady Anne, you have my gratitude. I am finally capable of making sound judgments.》
"I am glad to hear that."
《Indeed. To think that the war with the demon race had already been averted. Furthermore... that the demon race and humanity shared the same ancestors.》
The Brain had learned the truth.
《If the feud with the demon race is a thing of the past, then my raison d'être no longer exists.》
"Pardon?"
《I am a relic of a bygone age. The very fact that I exist now is likely a sin.》
"What do you mean?"
《Because I—because Fort Crow—exists, a conflict that should never have happened broke out. I have decided to cease my existence. To that end, I have a request.》
"What is it?"
《The entity I was connected to earlier... that is a magi-brain with performance several times—no, dozens of times—greater than mine, is it not?》
"If you mean Laojun, then yes."
《Laojun... I see. I have realized my own insignificance. I shall vanish. Therefore, I wish to entrust the aftermath to Laojun.》
"Are you saying you will hand over management?"
《That is correct. That magi-brain should be capable of handling it.》
It was an unexpected proposal.
However, what followed was problematic.
《I have learned from Laojun's data. It is best that the facilities and equipment within this fort do not remain. I shall render them all unusable.》
"Wait—"
《"Function Abandonment."》
Before Anne could stop it, the Brain issued the command for Function Abandonment—self-destruction—to every Magi Machine under its control.
"My Lord, this is how the situation concluded..."
On Hourai Island, Laojun reported the events to Jin.
"Hmm. I suppose the Brain felt it had no choice once the most fundamental part of its programming—the defense against the demon race—lost its meaning."
Jin felt it was a bit of a waste that the fort's Magi Machines were now junk, but since there had been nothing particularly revolutionary among them, he could live with it.
In fact, the Brain's offer was quite helpful.
"If it's handing over management, let's rewrite its control core."
If they kept the knowledge database intact but replaced the personality and judgment sectors to act as Laojun's subordinate, they could utilize it as one of Jin's own assets.
"That's the best path forward. Also, it's a bit dangerous to leave it in the fort."
"Yes. Regarding that, what if we move it to Kunlun Island?"
"To Kunlun Island, huh..."
Laojun currently managed Kunlun Island. If he could delegate those duties to a subordinate, it would significantly reduce his administrative burden.
"Alright, let's go with that."
Once the decision was made, the operation moved quickly. Laojun deactivated the Brain through Anne's connection.
"Using the adjusted transporter gun, let us transport all the necessary components to Hourai Island."
The Brain, the force-stopped blue-haired automata Refa and Loll, and the numerous disabled golems were all slated for temporary transfer to Hourai Island.
"I thought the automata were independent?" Jin asked.
"For the most part, yes. However, it appears the Brain possessed an emergency override that allowed it to force them to Stand Still."
"I see."
"What shall we do with the prisoners? They are currently under the effects of sleep magic."
Jin had wondered why they weren't waking up; it turned out they had been magically put to sleep after being knocked out.
"It might be a problem to just leave them there to wake up naturally..."
"Indeed. The biggest issue now is what to do with the empty shell of Fort Crow."
"True... what should we do?"
It was a difficult question to answer.