The cards came next. The tabletop game's cards were hand-drawn by Fujiwara Chika, each with a unique effect. The cards Amon drew always seemed to perfectly counter the current situation. When Shirogane Miyuki launched an attack, he happened to draw "Moat." When Ishigami Yu tried to steal resources, he happened to draw "Sentry Post."
"You've drawn another good card, haven't you?" Shinomiya Kaguya set down her teacup, her voice calm but her gaze sharp.
"The deck is randomized." Amon shuffled the cards in his hand. "I simply drew what I needed."
But that wasn't the only problem.
In the third round, Fujiwara Chika activated her trump card, "Reverse Trial"—a card that could nullify an action that had already taken effect. She announced triumphantly, "Now Amon-san's combo is going to be broken!"
Amon looked at the card, then at his own hand. "The effect of 'Reverse Trial' is to 'nullify one action within this turn,' correct?"
"Exactly!"
"Then I'll use 'Time Backtrack.'" Amon placed a card on the table. "Its effect is to 'rewind this turn to before the start of the action phase.' According to Article 3 on page seven of the rulebook, if a turn is backtracked, all card effects activated within that turn are reset."
Fujiwara Chika froze. She quickly flipped through the rulebook and found the clause—it was indeed written there.
"B-but 'Time Backtrack' is a rare card! How do you have it?" Her eyes widened.
"I drew it last round." Amon smiled gently. "Is there a problem?"
"…No." Fujiwara Chika gritted her teeth.
The turn was rewound, and everything reset. This time, Amon changed his sequence—he played "Reverse Trial" before Fujiwara Chika could, targeting one of her own buff effects.
"Wait! How can you use that on me?" Fujiwara Chika protested.
"The rulebook doesn't forbid using it on teammates." Amon opened the rulebook and pointed to a line of text. "It states: the target of 'Reverse Trial' is 'any one effect that has already taken effect.'"
"B-but—"
"No 'buts,' Student Fujiwara." Amon adjusted his monocle. "Rules are rules. You wrote them—you should abide by them."
Fujiwara Chika opened her mouth but couldn't respond.
Shinomiya Kaguya watched silently, her finger tapping lightly against the table. Shirogane Miyuki frowned, sensing something off but unable to articulate it. Ishigami Yu quietly shrank back, deciding to remain invisible.
The game continued.
By the fourth round, the balance began to tip decisively. Amon and Shinomiya Kaguya's "Kingdom" faction had accumulated an overwhelming advantage. It wasn't due to perfect teamwork—in fact, Shinomiya had failed to follow Amon's reasoning several times—but because every one of Amon's moves precisely exploited gaps in the rules.
He used "Trade Agreement" to take Shirogane Miyuki's key resources, citing that "the rules allow cross-faction trading." He used "Espionage" to check Ishigami Yu's hand, noting that "the effect description does not require the opponent's consent." He even used "Natural Disaster" to destroy Fujiwara Chika's main city—the justification being that "the card states it can destroy any one city on the map, and my city is also a valid target under that definition."
"But who would destroy their own main city?!" Fujiwara Chika exclaimed.
"I would," Amon replied calmly. "Because doing so triggers my 'Ruins Reconstruction,' yielding double resources. This is the optimal solution."
"B-but—"
"The rules allow it," Amon interrupted, his smile unchanged. "Your rules, Student Fujiwara. Every word, every clause—I have followed them precisely."
Fujiwara Chika stared at her ruined city, then at the pile of resources in front of Amon, and felt tears welling up.
She had spent three months designing this game, testing it countless times, refining every detail. She believed it was perfect—balanced, fair, and enjoyable.
And now, this transfer student was using her own rules to dismantle everything.
"Is there any need to continue?" Shinomiya Kaguya said calmly. "The outcome is already clear."
Shirogane Miyuki sighed. "I concede. Amon-san… you play very well."
"I concede too," Ishigami Yu added quickly.
Fujiwara Chika lowered her head, silent.
Amon looked at her. "Student Fujiwara, what was your purpose in designing this game?"
"…To let everyone have fun," she said quietly.
"And are you having fun now?"
She looked up, her eyes slightly red. "No! Not at all! You're not playing a game—you're solving a math problem! You've ruined everything!"
"Fun?" Amon tilted his head. "Isn't the purpose of a game to follow rules, apply strategy, and achieve victory? I have done all three. Where is the issue?"
"The issue is you're too 'correct'!" Fujiwara Chika stood up, her voice trembling. "Games need surprises, mistakes, luck, comebacks! The way you play… you're trampling on the spirit of the game!"
Amon looked at her quietly for a long moment.
Then he laughed.
Not a polite smile, but genuine amusement—his eyes curved, his shoulders trembling slightly.
"Trampling on the spirit of the game…" he repeated softly. "You're right. I am trampling—on your belief in 'correct rules.'"
He stood and walked to the window. Outside, the rain had stopped, but the sky remained overcast.
"You believe that clear, complete, and fair rules guarantee a smooth game," he said without turning. "But reality doesn't work that way. There will always be someone who finds loopholes—someone who follows the rules in ways you never imagined, someone who dismantles everything while staying perfectly within the rules."
He turned back, his monocle glinting faintly.
"That is 'Error.' Not breaking rules—but producing outcomes the rule-maker never anticipated within them. The more perfect the rules, the more interesting the error."
Fujiwara Chika stared at him, tears still in her eyes, but forgotten.
Shirogane Miyuki frowned. "Did you come here just to cause trouble?"
"Cause trouble? No." Amon shook his head. "I came to deliver documents—and to play a game. Student Fujiwara invited me."
Shinomiya Kaguya placed her teacup down with a soft click. "Then the game is over. You may leave."
"Of course." Amon bowed slightly. "Thank you for your hospitality. Especially you, Student Fujiwara—your game design is excellent. Truly."
He turned toward the door, then paused with his hand on the handle.
"Just remember to leave space for 'errors' next time. A flawless system is the easiest to break."
The door opened.
Then closed.
Silence lingered.
Fujiwara Chika suddenly burst into tears. "He's a bully! He used my own rules against me!"
Shinomiya Kaguya handed her a tissue. "But he did not break a single rule."
"That's why it's worse!"
Shirogane Miyuki rubbed his temples. "That transfer student… who is he?"
Ishigami Yu muttered, "When he left… I think his monocle flashed."
"Probably just a trick of the light."
"Maybe…"
Outside, the clouds parted slightly, revealing a pale moon.
Amon walked along the road back to Sobu High School, humming softly. His fingers moved in the air, as if plucking invisible strings.
"Rules…" he murmured. "Humans love creating rules—then trapping themselves within them. Schools, games, society, morality… layers upon layers of structure."
He stopped and looked up at the moon.
"But no matter how perfect the rules are, they cannot contain 'Error.' Because Error does not follow rules—Error is their opposite."
The monocle reflected cold moonlight.
"Next… who shall I play with?"
He thought for a moment, then smiled.
"That child hiding in the closet seems promising."
His footsteps faded into the night. The moon slipped back behind the clouds.