Shirou's Return from the Fae Kingdom

At that moment, Lady Avalon suddenly felt an unusual surge of magical power. This was...

"Master!!"

Lady Avalon urgently warned him via telepathy, but it was too late.

A bewitching crimson light bloomed between Shirou and Irisviel.

"What is this... what's happening?"

Shirou looked down. Something was pushing open Irisviel's coat and erupting from her collar, flying into the air.

It was Caster's Noble Phantasm, the "Tome of the R'lyeh."

"What's going on? Why is this Noble Phantasm still here?" Shirou asked, confused.

Irisviel apologized profusely, "I-I'm sorry. I thought you'd like it, Shinji-kun, so I secretly kept it. Because I wanted to read it to you later as a bedtime fairy tale..."

Shirou couldn't quite follow the woman's train of thought.

"Didn't Caster already return to the Throne?"

Saber looked up at the "Tome of the R'lyeh" rapidly flipping its pages in the air.

Gilles de Rais had vanished without a trace. Shirou's theory for why the Grimoire remained was that the magical spell that had already been cast was still ongoing. Previously, Caster had used the Grimoire to open an interdimensional portal to summon monsters. Even if he were killed, it wouldn't disappear; they could only wait for the portal's duration to end.

However, now, the Grimoire was emitting a far more powerful magical energy than before. The countless scattered flesh and limbs on the ground instantly transformed back into monsters from another dimension. They ignored Shirou and Saber, extending tentacles towards the Grimoire in mid-air, quickly engulfing it. The tentacles multiplied at an unimaginable speed, far beyond what they could before. Thousands of tentacles intertwined and merged, gradually forming a grotesque mountain of flesh and blood.

Saber was stunned. "Why? Who is continuously injecting magic into that Grimoire? Such immense magical power, how is it possible... Caster is already gone!"

Shirou narrowed his eyes and voiced a possibility. "There is only one person in this world who can forcibly activate Caster's Noble Phantasm, regardless of any conditions."

Saber and Irisviel's eyes widened upon his reminder.

"Caster's Master... Ryunosuke Uryu!"

In the darkness.

The young man sat quietly on the sofa. He had maintained this posture for three days. A normal human would likely suffer from necrosis in their thighs due to poor blood circulation, but he was already a corpse-person and had no such worries. No, Ryunosuke Uryu had long since lost the capacity for "worry." His brain was gone, his intellect was gone, his self was gone. At most, he could now only produce some reflex actions based on external stimuli, no different from a dissected frog in a laboratory. The young man named Ryunosuke Uryu had died the day he met the red-haired boy. What remained here was merely a piece of dead flesh inheriting his appearance.

Just now, Gilles de Rais had been killed. Although the Servant had disappeared, Ryunosuke Uryu's Command Spells had not, instead remaining attached to the back of his hand. This defied the rules of the Holy Grail War. Command Spells were essentially binding curses, a type of restriction added by Zouken Matou, who was skilled in curses, to control Servants. Since they were artificial, there were bound to be loopholes, even for a genius old Magus. He probably hadn't considered this situation—that the Servant's Master would be a corpse-person. The innate affinity between "undead" and "curses" allowed the Command Spells to miraculously remain on Ryunosuke Uryu's body.

And this was not the only coincidence that had occurred. Gilles de Rais had used the Grimoire to open a Soul-Absorbing Barrier in Fuyuki City, transferring the life force stolen from the citizens to his Master. During this process, Ryunosuke Uryu also gained Caster's life force. Combined with the magical energy pathway that already connected Master and Servant, they achieved a certain level of life-sharing—the "meat lump" (Ryunosuke Uryu) became another Caster (Gilles de Rais). This was the truth behind why the "Tome of the R'lyeh" had not disappeared after Caster's death.

Ryunosuke Uryu, this "dead man," inherited Caster's life and Noble Phantasm, and is still "alive."

Then, this cold lump of flesh that had long lost its sentience was acting uncharacteristically, performing actions that didn't fit the logic of a corpse-person.

"Ah... ah... Master..."

"I'm so unwilling... Master Bluebeard..."

The corpse-person gazed into the void with cloudy, unfocused eyes, muttering intermittently while consuming the Command Spells on its back.

"Kill them... kill them all..."

One.

"Unforgivable... I must... take revenge on them..."

Two.

"Master... let me appreciate something cooler... true art..."

Three.

Neither Magic nor science could explain what will was driving this mass of flesh.

But it happened.

If this were a fairy tale, this phenomenon could be defined as "the power of love creating a miracle."

But unfortunately, Bluebeard was merely a story removed from Grimm's Fairy Tales due to its excessive darkness and gore.

After exhausting all his Command Spells, Ryunosuke Uryu's last breath vanished.

He transformed from a mobile lump of flesh (corpse-person) into an ordinary lump of flesh (corpse), finally ending his sinful life.

Even so.

This thing that was once "Ryunosuke Uryu" still wore an expression of immense satisfaction on its lips as it passed away.

Normally, it's difficult for a Magus's Familiar to approach another Magus's barrier.

Therefore, Irisviel didn't pay much mind even though she knew the other parties had dispatched Familiars outside the forest; they wouldn't be able to scout anything anyway.

However, Caster's actions tonight were far too outrageous.

Not only did he openly step into the Einzbern forest in front of numerous Familiars, but he also attempted a blood sacrifice ritual afterward, opening the gate to another world.

This made it impossible for the other Masters to ignore the situation.

As all participating Masters focused their attention on the Einzbern territory, they detected the magical energy reaction of a super-large ritual Magic emanating from the forest.

Kenshinnes and his Servant, Demon Diarmuid, were currently searching for targets in Miyama Town, not far from the Einzbern forest.

For them, the primary target was Saber, who had defeated them once before in Warehouse District.

Now that the Einzbern side was in trouble, they wouldn't just stand by; it was a perfect opportunity to strike.

"Can you see what's happening, Lancer?"

The spear wielder, clad in the hide of a demon boar, peered through the thick night fog blanketing the city.

"It's Caster. The one who recklessly intruded into the Einzbern forest seems to be plotting something. ...What astonishing magical energy. With that amount, it's enough to destroy this city."

Kenshinnes frowned. "Doesn't that guy know he's been put on the Church's wanted list and is a target for all Servants?"

"If a madman had self-awareness, he wouldn't be a madman."

Kenshinnes's Familiar had just returned from Rin Tohsaka. The Church had just announced:

Due to Caster disregarding the secret rules of the Holy Grail War and committing various crimes near Fuyuki City, he has become a threat to the continuation of the ritual.

Therefore, an additional rule has been temporarily added: a Command Spell will be awarded to the Master who eliminates Caster.

The Einzberns, busy dealing with Caster's invasion all night, clearly hadn't received this information yet.

By the time they learned of this additional rule, the battle would likely be long over.

This was a significant advantage for Kenshinnes, allowing him to claim the prize all for himself.

He now had only one Command Spell left and was determined to obtain a new one.

"Hmph, let's go."

Kenshinnes headed towards the fog-shrouded outskirts.

"Tonight, they will know the consequences of opposing me, El-Melloi... but before that."

The man sneered and asked, "Answer me, Lancer. Who is your enemy? Is it the evil and insane Caster? Or is it Saber, who once brought you defeat and shamed the name of Diarmuid?"

"...Foolish question."

The black Lancer glanced back at him deeply, then replied in a tone devoid of any emotion.

"There is only one target to kill...

Saber's Master, Irisviel von Einzbern."

For Demon Diarmuid, the Lancer who had abandoned chivalry, the glory and joy of battle had long since become worthless.

Not only that, but even the act of swearing fealty to Saber was meaningless.

There was only one thing of value—

It was to commit every wicked and evil deed in the world by any means necessary, and to carve "victory" as the final outcome.

"That is..."

Irisviel's eyes widened in disbelief.

Caster continued to expand with unstoppable momentum, already reaching the size of a hill.

Without a doubt, that was the true form of the otherworldly fiend summoned by the "Tome of the R'lyeh."

Against the backdrop of the night, towering over the Einzbern forest, was the nightmare that ruled the otherworldly seas, a monster named "Sea Monster."

The endless tentacles of monsters that had appeared like a tide until now were not its kin or offspring, but merely the tip of the iceberg of its colossal body.

Fortunately, this was the outskirts of Fuyuki, far from the city center, so no casualties had occurred yet.

But even in the outskirts, a monster of this size could not go unnoticed.

Although it was night in the suburbs, confused shouts could still be heard from afar.

It was understandable that the citizens would be astonished to witness a scene like something out of a monster movie.

Fortunately, because the ritual magic had also generated a large amount of dense fog, people could not see the Sea Monster's full form.