"…This is dangerous. Nikola Tesla… this is not good. Not pleasant in the slightest."
Holmes was right.
Even putting other magi aside, that Servant… Archer-class Nikola Tesla was someone who could be definitively called a threat.
Pure physical electricity that cannot be blocked by the Preta Path's Seal Absorption, a Magic Resistance rank of C+—which was unheard of for a modern Servant—and even a boost from either the Holy Grail or the King of Demon Gods.
"I recommend surrender."
"…What?"
"Having received the power of 'That One,' I have come to recognize your struggle. Have you not fought long enough already? Look at the current situation. We have become beings who both exist and do not exist at the same time. By manifesting the 'Mafia,' it is safe to say that the possibility of restoring this Singularity has vanished."
"So… surrender? Because you don't want to take unnecessary damage?"
"No, our victory is inevitable. However… wasting time on such trivialities is a folly only fit for commoners."
…Is this guy serious?
"But I refuse!"
"I thought as much."
Nikola Tesla reached out as if it were only natural and fired a bolt of blue lightning toward me.
"◼︎◼︎◼︎◼︎◼︎◼︎◼︎◼︎◼︎◼︎◼︎!!!!!!!"
As if that bolt were the signal to attack, the other magi also began to rush toward us in their own ways.
Under normal circumstances, attacks from magi would be no match for a Servant. However, as if the 'Mafia' state provided some kind of buff, the enemies—stained pitch black and looking corrupted—hurled attacks that barely grazed Tristan and Holmes.
"…Quite troublesome. It might have been dangerous if I didn't have Magic Resistance… and yet!"
With a tring—the sound of a string being plucked—the heads of five or six blackened magi soared into the air.
"Hold on to those!"
I pulled the heads flying through the air toward me, then used Shinra Tensei to hurl them straight at Tesla.
The skulls, possessing the weight and mass of bowling balls, flew at supersonic speeds, scattering brain matter and blood. But Tesla, as if it were obvious, created a barrier of electric current and incinerated the skulls into ash.
"How barbaric. How is a detective like me supposed to make a living in such conditions?"
"Are you using that cane for soup? Conan Doyle even gave you that weird martial art, Baritsu!"
"Even so, it is difficult when three magi pounce at once!"
"Who cares! It's hard to protect you, so fight for yourself!"
At that moment, the spinning vision of the Rinnegan caught sight of a massive amount of prana condensing.
The prana was soon converted into electrical current, and a massive sphere of lightning… plummeted to the ground, grazing Tristan.
Tristan, who had narrowly avoided the lightning, quickly plucked his bow, aiming for the man's right wrist. But Tesla, using the electricity to levitate his body, began to spray current in all directions.
"…This bastard is attacking without even distinguishing between friend and foe!"
"Master, is it impossible to check him with your magecraft that absorbs prana?"
"It won't work! That's not prana, it's pure electricity… If it contained prana, I could kill its power by absorbing it, but pure electrical power is immune to the Preta Path! It's even difficult to block electricity with Shinra Tensei..."
Furthermore, the Six Paths of Pain I was using were fundamentally sophisticated puppets created by Touko Aozaki. While they were dolls that could be handled roughly without issue, they were essentially fake corpses made to mimic the human body. If exposed to such high-voltage power, they would become paralyzed and unable to move, just like a human.
Fortunately, the Mafia magi that had suddenly appeared were being cleared out by Tristan's diligent bow plucking… leaving only Nikola Tesla.
"…Tristan, how long can you hold out against him?"
"If I deploy my Noble Phantasm, I can keep him pinned for ten minutes."
"That's enough information. Let's get out of here!"
"Regrettably, I cannot let you leave."
"Who asked for your permission?!"
Unleashing a repulsive force, I blew away the two magi who were swinging at Holmes with their cane-swords, and I firmly grabbed both of their shoulders.
I had enough output to trigger Shinra Tensei, and no matter how great Nikola Tesla was, he had no means of chasing us instantly. If we just did this…
Rumble… CRAAA-ACK!
"…You've got to be kidding me."
At that moment, I witnessed the ground turning bright blue.
Even though Nikola Tesla was clearly firing electrical power toward us, lightning strikes began to erupt and surge from the ground we were standing on.
"This is… a return stroke! Lightning rising from the ground to the sky."
"…Damn it, so that's why he poured so much power into the ground!"
The man, with his hardened expression, was like an impregnable fortress.
Even when I fired attacks from the Asura Path, he blocked them with his solid Magic Resistance and barrier of electricity. When I tried to pull him in with Bansho Ten'in, he tried to roast me with electrical power instead.
"…If we continue this war of attrition, we'll lose. We need to retreat."
"I concur!"
"Who do you think will allow that?"
Then, I saw it.
A massive thundercloud, covered in enormous electrical power, was staining not just the interior of the Clock Tower but the entire sky of London blue.
"This body's power is the stride of humanity, the voices of the people… the rotation of the Earth. A lightning of man that transcends God, condensing all those powers!"
"[Humanity's Myth: Descent of Thunder - System Keraunos]!"
"MASTER!!!!!"
*
Looking at the spot where the intense lightning had just swept through, the Clock Tower that should have stood tall and the surrounding Mages' Association facilities had vanished as if turned to ash.
[…ma— …lish— …hed— …est— …Karma!]
"…This is Karma Kirigaya. Chaldea staff, please respond."
[Light— …rupt— …lem— …turn— !!!]
"It seems Nikola Tesla's electrical power has caused issues with the communication to Chaldea. But where is Tristan…?"
[This is Chaldea communication! A problem has occurred at Makiri Zolgen's workshop! I repeat, Zolgen's workshop has been breached. Requesting immediate backup!]
"The situation we feared has come to pass. We should retreat immediately with Tristan, Master!"
"…Right."
As I picked him up and secured him to my shoulder, Sherlock Holmes shouted loud enough to make my ears ring.
"Wait, what do you plan to do about Tristan? If you are planning to have him buy time against Tesla, I must evaluate that as an incredibly flawed plan!"
"…It wouldn't even buy time in the first place. He's already been unsummoned."
"What…?"
"Damn it, you're a detective and you don't even know that? It was impossible to block that lightning through physical means! If I had used the Tsar Bomba, the whole of London would have been blown away, and my or your defense wouldn't have stood a chance…"
If the prana path connected to him had vanished, and the massive thundercloud covering all of London had disappeared entirely, there was only one possibility.
"That guy… he overloaded his own Saint Graph and self-destructed!"
"…I see. So that was it."
"Anyway, Nikola Tesla won't be able to fire an attack of that scale a second time. We need to get back to the workshop. if Zolgen's workshop was breached… Ritsuka will be in danger."
Then, Waver's voice came through from Chaldea.
[Relax. Ritsuka Fujimaru is safe.]
"…What about the other Servants?"
[Nursery Rhyme sustained some injuries, but not enough to cause unsummoning. She's currently being healed by Zolgen's magecraft, so there's no problem. However… Kiyohime was attacked by the enemy Assassin and has been unsummoned.]
"Did they catch that Assassin… Jack the Ripper?"
[Gareth succeeded in landing a blow with her lance, but the Assassin escaped into hiding. Regrettably, we're too busy just repairing the workshop to go out into the city to search for her.]
Traveling at a speed that almost overheated my Magic Circuits, I arrived at the workshop. The door opened, and a somber-looking Zolgen guided us inside.
"Bad news, young man. It seems the enemy has found the weakness in my workshop."
"…It wasn't breached because of the King of Storms?"
"No, the King of Storms did not appear this time. Instead, Jack the Ripper succeeded in finding a flaw in my workshop and forced her way in. I tried to suppress her with the internal interception system, but before that, Miss Kiyohime's Saint Graph was pierced… she was unsummoned."
"It couldn't be helped. The opponent is an Assassin who is the natural enemy of women… By any chance, is it possible to summon a Servant using only the equipment in this workshop?"
"That is impossible. While I can produce and store enough prana to operate the workshop and its defense systems, at least for this workshop, it cannot handle the burden of summoning a Servant."
That meant it was also impossible to bring in other Servants who were on standby at Chaldea—like Elizabeth or Altera—due to resource issues.
"However, one thing is certain."
"What?"
"There is a traitor—a Judas—among us."
It wasn't an attack from the King of Storms, and it should be absolutely impossible for just one Assassin to breach Zolgen's workshop, which possessed defenses on par with a Servant.
Setting aside the elemental advantage of a Caster against an Assassin, Zolgen's magecraft was more than enough to prevent the intrusion of any Assassin ranked below Hassan-i-Sabbah.
"…But Master, did you not interrogate everyone else with me last time? 'Are you on the side of the King of Demon Gods?', 'Are you an enemy of the Human Order?', 'Are you an enemy of Chaldea?'—with those three questions."
"Right, we certainly did."
"Could it be that you've discovered another truth that I am unaware of? If so, I would very much like to hear it."
Holmes's words sounded like sarcasm at first glance, but this Advisory Detective's eyes were sparkling as if he were focusing solely on the fact that he could satisfy his own curiosity and inquiry, despite the seriousness of the situation.
"It seems you're more delighted that I found out something you didn't."
"Do you have any idea how heart-pounding it is to find a riddle I cannot solve? At any rate, please tell me quickly. My brain is getting excited at the prospect of a new mystery."
Before I knew it, everyone else in the workshop… Zolgen, Ritsuka, Gareth, Mash, and the resident Servants, Henry Jekyll and Nursery Rhyme, had all gathered.
Waver connected the two writers at Paracelsus's workshop and Paracelsus himself through Chaldea's communication, and I cleared my throat slightly before beginning to explain my hypothesis.
"First of all… does everyone remember the test I performed? The test I did by summoning the Hell Realm."
[Certainly. You asked each of us if we were on the side of the King of Demon Gods, if we were enemies of Chaldea, and if we were enemies of the Human Order… those three things.]
"The truth of the Hell Realm is about whether an individual truly believes something to be true or false. Because of that, in the case of a Servant who is on the side of the Human Order but has been brainwashed, it would be impossible to notice."
[I-I see! If that's the case, then it's possible the Hell Realm wouldn't react...]
"However, that is impossible, Master Waver. I would have been the first to notice."
[…Is there not a possibility that you have betrayed us?]
"Of course there is. But if that were the case, would Chaldea's Master, who possesses eyes capable of reading prana, not have noticed?"
[Ah…]
"It's just as he says, Waver. The possibility that a Servant was brainwashed is zero."
My mind was spinning as if it were on fire, and the mysteries scattered like a 1,000-piece jigsaw puzzle began to fit together as one.
"The remaining possibilities are two. Either the Servant is such a great liar that they can deceive the Hell Realm, or they can somehow neutralize it. But fundamentally speaking, it's impossible to neutralize the Hell Realm."
"…And why is that? I hate to say it myself, but there are more types of magecraft that neutralize lie detection than one might imagine. Furthermore, if our enemy is the King of Demon Gods who possesses abilities that transcend human wisdom…"
"Of course, I expected as much. But let alone an ordinary magus, even the King of Demon Gods cannot interfere with my ability. More accurately, it's easier to think of it as a mutual counter."
Abilities derived from the Root decrease in power the more they face Evils of Humanity.
That is why the observation of worlds of the Second Magician or Aoko-nee-san's Magic Bullets using 'Blue' decreased in power when facing Angra Mainyu.
"The same goes for my ability of the Six Paths of Reincarnation. It's impossible to unleash its full output against the King of Demon Gods, but the same goes for him. That guy cannot purely damage my ability itself. If he could, he would have sealed my ability long ago… Since what I use is strictly magecraft, and he is essentially the sum of all modern magecraft."
"I see… Then what about magecraft that neutralizes lie detection?"
"Do you really think an ability derived from the Root can be neutralized by the magecraft of other magi who are subordinate to the Root?"
Of course, it might be different in the case of a magus from the Age of Gods who was always by the Root's side… for example, someone like Medea. But the only ones here who touch the Age of Gods are Mordred, Gareth, and Mash, who received Galahad's Spirit Foundation.
Even Paracelsus, if you think back to how he was defeated by Manaka in the Tokyo Holy Grail War that originally took place, the Root is something inaccessible to magi.
"Therefore, only one possibility remains. It means our opponent is a liar so immense that they surpass the Hell Realm. More accurately, they are someone who tells lies that cannot be captured even by the Hell Realm."