FGO System in the Type-Moon World

A serial killer.

A man who took pleasure in slaughtering the innocent.

A man who, in the original timeline, would have become the Master of Caster.

Uryuu Ryuunosuke.

To many, he was nothing more than a heinous criminal.

But to Uryuu Ryuunosuke, he was an artist.

Every time his knife tore through flesh, he felt a thrill—a pulse of exhilaration that coursed through his body.

At first, he had been content with just stabbing his victims.

Then came dissections.

And now?

Even dissecting his victims no longer satisfied him.

And yet, it had only been a few years since he started.

A human's lifespan lasted decades—so what would he do if he lost all his enjoyment so soon?

That was why, one day, he began to seek new thrills.

And then—he noticed the red markings that had suddenly appeared on his hand.

Curious, he had returned to his family home, searching through his ancestors' records.

It was there that he discovered something fascinating—a magic circle, carefully detailed in the old texts.

A summoning ritual.

A ritual to summon a Servant.

Ryuunosuke found this utterly amusing.

But there was a problem—

He wasn't very skilled at drawing it.

He had messed it up multiple times already.

And since the circle's foundation required human blood…

It was easy to imagine what he had been doing lately.

By all accounts, today should have been just like any other day.

He would go out to buy some food, do a bit of hunting, and then return to his dark little room to continue his art.

And today, he had indeed found a target.

Originally, this person wasn't within his hunting criteria.

Because adult men—especially grown men—no longer excited him.

But this time—

The man had been following him.

And that gave Ryuunosuke an excuse to kill him.

After all, he was a serial killer—

Not some reasonable guy who would just let things go.

He figured the man was just another desperate mugger, hoping to rob him.

How foolish.

With that thought in mind, Ryuunosuke silently led his pursuer to a secluded location—

No people.

No cameras.

No police patrols nearby.

Then, with his back still turned, a twisted grin spread across his face.

To Ryuunosuke, this was just another successful hunt.

But to Reiji Souma?

It was just laughable.

He couldn't quite understand why Ryuunosuke would so willingly lead himself to the perfect graveyard.

Did he want to die somewhere quiet?

He found it pointless to ask.

After all, he wasn't here to pass judgment.

He wasn't going to say,

"Because you're a murderer, I will bring you to justice."

Nor was he going to say,

"Because of the atrocities you would commit in the future, I will stop you now."

No.

His reason was far simpler.

"…I need to test something. So, you're going to die now."

Then, without hesitation—

"Berserker."

At first, Ryuunosuke didn't understand.

Then—

A flash of lightning split the sky.

And with it—

A towering black-and-red figure appeared before him.

A monstrous weapon in hand—one that was like a spear, yet bore razor-sharp, claw-like barbs.

The weapon swung forward, breaking the sound barrier, the impact erupting in a sonic boom.

The friction alone was enough to ignite flames, instantly evaporating the blood in the air.

Before Ryuunosuke could even comprehend the pain—

It was already over.

His head was pierced through, instantly obliterated.

His headless corpse fell to its knees, then collapsed into the growing pool of blood.

Another flash of lightning streaked across the sky.

Reiji stood still, his back to the corpse, his eyes slowly widening.

Because at that moment—

His system, which had been silent for so long, finally spoke.

[First Master Kill Achievement Unlocked]

[Reward: One Free Caster-Class Servant Summon]

[Note: Achievements can only be obtained once, and their conditions will not be displayed beforehand.]

Reiji read through the message, nodding to himself.

There were no Saint Quartz rewards this time—

Which meant he had just confirmed the system's mechanics.

It seemed that only killing Servants would grant him Saint Quartz.

But a free Caster summon…

That was convenient.

He had been in need of a stronghold, after all.

And this—

This was the perfect opportunity.

With a grin, he cracked his neck.

"Looks like it's time to test my luck again."