C_n = P(1+r)^{n-1}
"This is the exponential growth model," Hori explained, pointing at the variables with the tip of his pen. "C is the cost. P is the principal, which is 100,000. And r is the rate, 0.10. Look at the paper. If I buy the first seat, it costs 100,000. If I buy the second, it costs 110,000. The third is 121,000. Do you see the pattern?"
Hirano nodded slowly. "It keeps getting more expensive."
"Exponentially more expensive," Hori corrected sharply. "If Class A has 3.76 million points, why don't they just buy thirty seats from us and enslave the entire classroom immediately?"
Hirano stared at the formula. She chewed on her bottom lip. "Because... the tenth seat would be really expensive? And the twentieth would be even worse?"
"The curve goes vertical," Hori stated. He drew a sharp line curving aggressively upward on the paper. "To buy twenty-five seats from a single target class would cost millions upon millions of points. It would instantly bankrupt them. The system's compound interest is an absolute mathematical ceiling. It prevents a wealthy class from launching a blitzkrieg and wiping out a weaker class on day one."
Hirano's eyes widened. "So how did they buy twenty-one of our seats?"
"Think," Hori commanded. "If the penalty only applies when you buy repeatedly from the same target, how do you bypass the penalty?"
Hirano stared at the paper. The gears in her head were grinding. She looked at the upward curve. "You... you stop buying from that target. You buy from someone else."
"Diversification," Hori confirmed. "Class A didn't buy twenty-one seats from us. They bought nine. They spent 1.35 million points to hit us. Then they stopped, because the tenth seat was too expensive. They took their remaining capital and bought seats from Class B and Class C instead. They spread their attacks to keep the base cost low."
Hori tapped the paper hard.
"Class B did the exact same thing. They took seven of our seats. Class C took five. Nine, plus seven, plus five. Exactly twenty-one seats. It wasn't random malice, Hirano. It was maximum mathematical efficiency. They calculated the exact ceiling of their starting capital and launched a synchronized, diversified hostile takeover."
Hirano stared at the numbers. Her hands were shaking slightly. The sheer coldness of the math was terrifying. It wasn't bullying.
"Okay," Hirano swallowed hard. "Okay, I understand the attack. But what about defense? Can't we just buy them back? If we save our points next month... if we pool our earned points together, we can just pay the 100,000 and free someone, right?"
Hori let out a harsh, mocking breath.
"You didn't listen to a word the teacher said," Hori sneered. "What is the Retrieval Law?"
Hirano flinched. "The... Highest-Cost-First protocol?"
"Explain it."
"I can't. I don't know what it means."
Hori flipped to a new page. He wrote the number 1 through 9 in a vertical column.
"Class A bought nine of our seats," Hori said, his voice entirely devoid of pity. "Seat one cost them 100,000. Seat two cost them 110,000. Seat nine cost them 214,358 points. If we want to save a classmate from Class A's acquisition, we cannot buy back the cheap 100,000 point seat. The system legally forces us to buy back their most expensive asset first. We have to pay the cost of the ninth seat."
He circled the massive number at the bottom of the list.
"214,358 points," Hori repeated. "Let's assume a hypothetical scenario. Our class magically acquires 215,000 points next month. We have a choice. We can either buy back our ninth seat from Class A, freeing one of our classmates. Or, we can use that capital to buy seats from other classes. Which is the correct move?"
Hirano looked at the numbers. "I... I want to save our classmate."
"Look at the math," Hori demanded. "If we spend 214,358 points to buy back our own seat, what is our return on investment?"
Hirano thought for a second. "We stop paying the 10,000 rent for that person."
"Correct. Our liability drops by one. But our income generated from that asset is zero. We spent 214,000 points just to get back to a neutral zero. Now, apply the other option. If we attack Class B and Class C with that same 215,000 points, how many of their first-tier seats can we afford?"
Hirano calculated the base cost. "Two?"
"Exactly. We buy the first seat of Class B for 100,000, and the first seat of Class C for 100,000. We spend 200,000 total. We now hold two foreign assets. And how much rent do those two assets pay us every month?"
Hirano's eyes widened. "10,000 each... so 20,000."
"Now weigh the board," Hori said, his voice cold. "On one side, we are tenants for one seat, costing us 10,000 in expense. On the other side, we own two foreign seats, generating 20,000 in income. What is our net gain?"
"A net gain of 10,000 points."
Hori dropped his pen. It clattered against the desk.
"The system heavily penalizes defense. It makes saving your own people exponentially harder than attacking your enemies. The only logical, mathematical move is to spend our capital immediately on offense. We force students from other classes to pay us rent. We attack!"
Hirano covered her mouth with her hand. "Is the system designed to make us cannibalize each other? That's horrible!"
"It is real estate," Hori stated coldly. "It is a monopoly. You do not win Monopoly by hoarding cash. You win by buying the board entirely. Once you own the ground the other players stand on, they bleed out just by existing. We are currently the tenants. We are bleeding."
I sat in the background, keeping my face perfectly blank.
Hori Seiji is highly intelligent. He sees the board with absolute clarity. He understands the hostile mechanics of the Seat Economy perfectly. He deduced the exact strategy of the upper classes within a few hours of the rules being revealed.
He is a great asset to the class.
"Do you understand now, Hirano?" Hori asked. His voice dropped into a vicious, lethal register. "Look at the reality of our situation. The school provides our meals in the cafeteria. They provide our uniforms, our dorms, our electricity. Our parents paid exorbitant tuition in the outside world to guarantee our physical survival here. Therefore, SC points have absolutely zero utility for daily life."
Hirano looked up at him, her eyes trembling.
"But if our parents already paid for everything..." Hirano's voice shook, her eyes pleading with him. "If our physical survival is already guaranteed... then why do these points even exist? Why force us to pay rent for a seat?"
I observed the micro-expressions on her face. Her breathing was shallow. She already possessed the data to answer her own question, but her brain was likely rejecting the conclusion to protect her emotional stability. It was a standard psychological bargaining tactic. She asked a question she already knew the answer to, desperately hoping Hori would contradict the math and offer her a moral safety net. A completely irrational expectation.
"Because they are not meal tickets," Hori stated, delivering the final, crushing blow. "They are not designed to buy food or clothes. They are pure, unregulated corporate capital. They exist for one single purpose: to wage financial warfare on this grid. We are fighting for our right to exist in this facility and Class D just walked onto a battlefield with empty hands."
Hori stood up. He did not wait for her to recover or argue. He shoved his notebook into his bag, zipped it shut, and slung it over his shoulder.
He walked down the aisle. His footsteps echoed sharply against the synthetic floor. He reached the sliding glass door at the front of the room. He stepped out into the hallway and disappeared.
Hirano remained frozen in the chair. She stared down at the piece of paper Hori had left behind. The equations were written in harsh, black ink.
The math did not care about her desire to make friends, nor did it care about her tears.
I stood up from my desk and picked up my bag.
Hirano blinked, pulling herself out of her stupor as she heard my chair scrape against the floor. She quickly stood up and grabbed her pink notebook.
"Asakura-san," she said, her voice lacking its usual bright energy. "Are you heading back to the dorms?"
"Yes."
"Can I walk with you?"
I looked at her. She was seeking proximity to mitigate her anxiety. Refusing her would require more energy than simply letting her walk beside me.
"Sure," I said.
We walked out of the academic building. The afternoon air was warm. Students from other classes were scattered across the courtyard, laughing and drinking from vending machines. They looked like normal high school students. Of course they were.
Hirano walked beside me in silence for three full minutes. It was highly unusual for her.
"He's really intense, isn't he?" Hirano finally asked as she looked down at the pavement. "Hori-san, I mean. He just looks at the numbers. He doesn't even consider how terrible it feels to abandon one of our own."
"Right," I replied.
"I just... I want everyone to get along," Hirano continued, forcing a weak smile onto her face. "Even in a system like this. If we all work together and help each other, maybe we don't have to attack anyone. We can just survive."
An irrational objective. The math strictly forbids pacifism.
"Maybe," I said.
Hirano looked at me. She tilted her head slightly. "You never really say much, do you, Asakura-san? You're always so quiet. I talk to almost everyone in class, but I feel like I barely know you."
"I have nothing to say."
"That's not true," Hirano laughed softly, though it sounded strained. "Everyone has something to say. Do you like the cafeteria food? I think the curry on Tuesdays is pretty good."
"It's fine."
She tried again. "Did you bring a lot of stuff from home? I packed three bags of clothes, but my room still feels empty."
"No."
Hirano sighed. She did not look offended but she seemed exhausted. The combination of the zero-point shock, the midterm threat, and Hori's brutal reality check had probably drained her battery.
"I guess I just hate seeing people alone," Hirano murmured, looking up at the sky. "It makes me anxious. That's why I try to talk to everyone. I want to make sure nobody gets left behind. Even you, Asakura-san. I want us to be friends."
I looked at her bright, desperate face. She was the absolute antithesis of my psychology. She relied entirely on social algorithms to function.
I reached into my blazer pocket. My fingers brushed against the smooth glass of my phone. I thought about the single contact name resting in my digital list.
"Right," I said.