What Holy Grail War? Let's Play Cards!

"You... I..." Facing the object in Jiang You's hand, Irisviel was at a complete loss for words.

"That expression—do you want this thing?" Jiang You waved the Soul Crystal in his hand. Seeing Irisviel staring at it so intensely, her soul practically leaving her body, he simply handed it over.

"Here, take it. I don't even know what it does. Do you?" Jiang You still hadn't figured out the significance of the object. After all, the Third Magic had never been concretely explained in the story—it was always left vague. And to him, this was still a Konami game; anything sent via in-game mail should logically be related to Yu-Gi-Oh! in some way.

Irisviel, unable to believe her eyes, took the crystal with trembling hands, as if it were a sacred relic. Her expression fluctuated wildly between crying and laughing, so much so that Jiang You began to suspect that her AI had bugged out.

"Lord Caster... Thank you. Truly, thank you. The Einzbern family will never forget this debt of gratitude." Irisviel carefully wrapped the crystal layer by layer, even casting a small-scale ward to keep bystanders away.

At that moment, Jiang You received a system notification:

You have obtained:

Irisviel von Einzbern ×2

Dress of Heaven ×2

[Additional affection-based rewards…]

The haul was extremely generous—the only downside was that it wasn't a full set of three.

"Oh, so it's an affection item? You should've said so earlier!" Jiang You had an epiphany and started analyzing the possible sources of Soul Crystals.

Meanwhile, Irisviel had already dropped to her knees before Jiang You, endlessly reciting words of gratitude. After listening for just a few moments, Jiang You quickly pulled her up—he was so embarrassed that he nearly burrowed through the airplane floor.

Once she finally regained her composure, Irisviel made a solemn request.

"Please allow me to return home. I must bring this wish back to my family."

"Huh?"

Upon hearing Irisviel's sudden decision to return, Emiya Kiritsugu—his face still bruised—looked utterly baffled.

"You mean, right after landing, she immediately booked a return flight? What exactly did you give her?"

"A Soul Crystal. Judging by its effect, it's an advanced affection item—probably on par with a Love Potion Cake. I'm kinda curious—if I gave you one, what kind of cards would you drop?"

"...You really have a way with words. Cards are all you ever think about. No wonder your Noble Phantasm turned out the way it did." Kiritsugu rubbed his forehead, trying in vain to understand Jiang You's mindset. "Do you realize how valuable that thing is? It's worth enough to bribe every participant in this war into rigging their fights for you."

"That makes it sound like I'd instantly get swarmed by a mob screaming 'Survival of the fittest!' the moment I pull one out. Next time, I'll give you one. I don't really care about the rest—but that 'Painful Choice' of yours? I'm taking it."

"...It was a mistake discussing this with you. Let's just go over the intel I gathered instead."

Kiritsugu detailed the identities of the Masters he had identified. Surprisingly, they all matched the original timeline. The only notable difference was that Ryuunosuke Uryuu was already dead. After confirming Uryuu's status, Kiritsugu had successfully identified all participating Masters early.

"So Uryuu is dead... That means I probably figured out where the Soul Crystal came from."

Jiang You examined the cards he had received. Since he had taken the Caster class, the system must have misassigned Gilles de Rais as Saber. Due to an ideological clash, Gilles had likely killed Uryuu, but then lost his source of mana and vanished from the war.

By comparing this to past card rewards—like the Illya-related card he obtained from fighting Kiritsugu—he deduced that the Soul Crystal was originally meant to be a reward for defeating Gilles de Rais.

"If Jeanne d'Arc's presence triggered Gilles' exit reward, then the Soul Crystal must be linked to Uryuu's death..."

Jiang You's gaze instinctively shifted toward Kiritsugu.

Kiritsugu immediately tensed up, his hand nearly reaching for his Origin Bullet.

"Relax. I'm not going for a genocide run this time—I still want to enjoy the story. Besides, we can't even be sure that a Master's death always results in a Soul Crystal drop. Fortunately, we have the perfect test subject right here."

Jiang You tapped the document on the table—a dossier on the Matou family.

Kiritsugu quickly tried to talk him out of it.

"It's still early in the war. If you act recklessly, you'll expose too much of your deck's mechanics. That would put you at a huge disadvantage in future duels."

"You just don't get it. Combat. Is. Fun."

Since Irisviel's departure had thrown off his original schedule, Jiang You had spent the entire afternoon wandering around Fuyuki in 2004, experiencing the local atmosphere. But now? Now his dueling urge had kicked in.

There was no way he'd listen to Kiritsugu's warnings now.

With that, he bolted out the door—running, jumping, rolling, crawling—all at inhuman speeds straight toward the Matou estate.

Kiritsugu, speechless, watched Jiang You's ridiculous, parkour-esque movement style draw the attention of every passerby. At this rate, he worried that his own characterization would get derailed by sheer association.

But what else could he do?

Facing a Servant who could casually hand out materialized fragments of the Third Magic, Kiritsugu had no choice but to adapt.

Sighing, he reached for his emergency contacts.

"Hello? Yeah, I need you to notify the Church. Tell them to clean up any collateral damage. Just say..." He pinched the bridge of his nose.

"Just say it's a street performance."

-

[Matou Manor]

"Alright. Combat movement test complete. No issues detected. Rating: Very satisfying. Though honestly, it feels kinda out of place in a card game. Is Old K running some kind of experimental build?"

Not long after, Jiang You arrived at the Matou estate.

Since he was here to pick a fight, there was no need for politeness.

With a single, forceful kick, he sent the main gate flying and stormed inside.

A withered old man sat in the living room, awaiting his uninvited guest.

After all, for a seasoned Magus, noticing a large, bizarrely moving entity approaching his workshop was far from difficult.

Matou Zouken had already activated his defensive spells and was ready to welcome his visitor.

"What brings you here in such a hurry, young man?"

"Old bastard! Drop some loot!"

Jiang You couldn't be bothered with pleasantries.

He immediately activated a duel challenge—dragging the Shadow Game into effect along with it.

"Oh? You dare storm a Magus' workshop alone? Should I admire your courage or mock your foolishness?"

Scanning Jiang You's Spiritual Core, Zouken sneered, preparing to dissolve into his swarm of insects.

He would use the home-field advantage to whittle down this third-rate Servant at his leisure.

But then—

[Caster has challenged you to a Duel. Do you accept?][Duel / Combat]

A foreign system prompt appeared before Zouken, and the surrounding space locked down.

His escape was cut off.

Even the workshop's defensive spells had stopped responding.

"This... is a Noble Phantasm? But there was no activation sequence... No. This must have been active long before now."

Zouken processed the data in his mind, chuckling.

"Hohohoho... Very well. It's been a long time since I've had fun. Let this so-called duel entertain me."

He accepted the challenge, utterly confident in his immortality.

"DUEL!"