Yukino Yukinoshita: "Volumen Hydrargyrum... is that Kayneth's trump card Mystic Code? I must say, it looks genuinely useful."
Kiana Kaslana: "Whoa—it looks so versatile! I wonder how it compares to Auntie's Judah. Hey, I wonder if it can help me with my homework?"
Theresa Apocalypse: "Hey, Kiana! You're secretly watching the light screen during class again! Damn it, don't you dare leave after class! I'm going to smash you with Judah and let you experience just how many uses it has!"
Kiana Kaslana: "Waaah—Auntie, I was wrong!"
Otto Apocalypse: "Objectively speaking, the versatility and power of Volumen Hydrargyrum should be inferior to the Oath of Judah. However, as a magus's trump card, balancing both defense and offense, its capabilities are indeed outstanding."
Utaha Kasumigaoka: "I really don't know what to say. Marching right into someone's territory to fight them... he's really not afraid of getting wrecked—"
Gilgamesh: "That is how it is with mongrels who are conceited about their own abilities. There is nothing to be said even if they die at the hands of another."
Archer (EMIYA): "Are you sure you're qualified to say that about him?"
---o---
[On the light screen, the events continued to unfold.
As Kayneth finished his monologue at the entrance and began to move deeper into the old castle, the camera shifted to a room somewhere inside. Emiya Kiritsugu had instructed Maiya Hisau to evacuate Irisviel through the back entrance, while he himself stayed behind to deal with the intruder.
The entire castle was filled with surveillance cameras. Emiya Kiritsugu monitored the images using a single laptop.
Cameras, explosives, firearms... perhaps only Emiya Kiritsugu could bring these things, completely unrelated to magecraft, into the Holy Grail War.
As Kayneth drew closer, Kiritsugu prepared to close his laptop and withdraw. He wasn't foolish enough to go one-on-one with a magus of this caliber.
While preparing to retreat, Kiritsugu analyzed the castle map in his mind, walking out of the room and toward the door—but he stopped just as he was about to open it.
From the keyhole of the door, a drop of mercury hung like a spider's thread. Although it was just a tiny amount, he could still see it leaving a silvery trail on the door's surface as it dripped downward.
The instant Kiritsugu saw it, the mercury drop suddenly stopped falling. Then, as if it were a living creature, it retreated along its original path back into the keyhole and vanished.
"...I see. 'Automatic Target Acquisition,' is it?"
Muttering these words, Emiya Kiritsugu immediately turned around. What he saw was the spot he had just been in—the large table—being instantly sliced in a perfect circle by blades of mercury.
Then, with a loud rumble, the severed section collapsed, and Kayneth, standing atop the Volumen Hydrargyrum, ascended through the gaping hole.
"Found you, little mouse!"
Kayneth stood with his arms crossed over his chest, a triumphant smile on his face.
Before the gloating Kayneth could order the mercury to attack, Emiya Kiritsugu had already drawn a submachine gun from his holster and opened fire.
The Volumen Hydrargyrum reacted instantly, forming a protective film in front of Kayneth, completely nullifying the power of the hail of bullets. The fifty-round magazine was emptied in just a few seconds.
However, those few short seconds gave Kiritsugu more than enough time to chant an incantation.
"Innate Time Control—Double Speed!"
As he chanted the spell, the magical energy within Emiya Kiritsugu's body began to surge violently.
In that instant, red magical energy enveloped his body. The color of the surrounding scenery faded from his vision, as if space itself were distorting. His speed suddenly accelerated, and with a sideways dash, he dodged the mercury's slash at the last possible second and escaped through the hole the Mystic Code had created.
The next moment, the scenery returned to normal. The Volumen Hydrargyrum's attack missed its mark, slashing through the wall and floor where Kiritsugu had been, kicking up a cloud of dust and smoke.
Only then did Kayneth belatedly realize that Emiya Kiritsugu had fled. As a top-tier magus, he recognized the method Kiritsugu had used at a glance.
"I see. You turn the inside of your own body into a Bounded Field to manipulate time and accelerate? It seems you have learned some magecraft after all."
"To think that someone who has at least been educated in magecraft would become a despicable person who relies on such lowly tricks. Death will make you recognize your place."
Speaking these words, Kayneth immediately returned to the lower floor, commanding the Volumen Hydrargyrum to give chase. The mercury extended numerous sentient, tentacle-like feelers, beginning to search in every direction and every corner.
From here on, the battle became a game of cat and mouse, as expected. Emiya Kiritsugu had no intention of fighting Kayneth head-on and was constantly on the run. He possessed none of the pride or self-respect that a magus should have.
Although he was completely on the back foot, by relying on his unique magic, Innate Time Control, the numerous traps scattered throughout the old castle, and various firearms, the two sides were engaged in a back-and-forth struggle. All of Emiya Kiritsugu's traps were based on modern technology rather than magecraft, and because of this, Kayneth could not guard against them. If it weren't for the Volumen Hydrargyrum, he would have been a corpse long ago.
The battle between the two was incredibly fierce, filled with constant explosions. An uninformed observer might have thought that two armies were engaged in urban warfare inside the old castle.
Moreover, the castle had a basement in addition to its above-ground floors, so Kiritsugu led Kayneth on a chase throughout the entire structure, resulting in a stalemate.]
---o---
L: "Innate Time Control. So this is Emiya Kiritsugu's magical technique? It looks quite extraordinary."
Otto Apocalypse: "Indeed. An ability related to time, even if it's just a trick, is quite formidable. Based on this alone, Emiya Kiritsugu's proficiency in magecraft is quite impressive among the broader community of magi."
Conan Edogawa: "A Magus Killer using magecraft... but that makes sense. It would be impossible for a Magus Killer to have zero understanding of magecraft and still hope to kill magi."
Eriri Spencer Sawamura: "It's a shame that even though Kiritsugu's magecraft level is high, it's still far from being a match for that Volumen Hydrargyrum."
Utaha Kasumigaoka: "Automatic target acquisition, automatic tracking, automatic defense... a fully-automated Mystic Code. No wonder it has Kiritsugu on the ropes. That thing could probably even fight some of the weaker Servants."
Kayneth El-Melloi Archibald: "Hmph. As the heirloom treasure of the Archibald family, how could it possibly fail to handle an attack of this level?"
Emiya Kiritsugu: "It is indeed a very troublesome Mystic Code. Without prior knowledge of its functions, it is highly likely it would have killed me."
Emiya Kiritsugu's eyes narrowed slightly. A Mystic Code like that was indeed incredible, but as long as it couldn't kill him on the first encounter, Kayneth's chances of victory were slim to none...