The rumor about the challenge had now reached its most unstable stage.
Rei understood this the moment she entered the school grounds the following morning.
Students who had nothing to do with Class D were talking about it.
Not because they cared about Yamauchi.
But because conflict inside the school always attracted attention.
Advanced Nurturing High School was a competitive environment by design. Even small disturbances could ripple outward when they involved pride, reputation, or perceived intelligence.
And Rei had introduced all three.
She crossed the courtyard calmly.
Several students glanced at her.
A few whispered.
None of them approached.
That was expected.
Attention often existed at a distance first.
Direct confrontation came later.
When Rei entered Class D, the shift inside the room was immediate.
Students were louder today.
More energetic.
The challenge had turned into entertainment.
Some students were even openly discussing what would happen if Yamauchi lost.
Rei walked to her seat and placed her bag down.
She noticed Yamauchi immediately.
He was sitting more rigidly than usual.
Two textbooks lay open in front of him.
He had probably been studying earlier.
A predictable response.
Pressure created preparation.
Rei sat down quietly.
Then she opened her notebook.
And began writing.
"Good morning."
Kei's voice arrived right on schedule.
Rei looked up.
Kei was standing beside the desk again, but her expression looked slightly different today.
More focused.
"You're earlier than usual," Kei said.
"Yes."
"Studying?"
"No."
Rei turned the notebook slightly so Kei could see.
The page was filled with small observations written in neat lines.
Behavioral notes.
Reaction patterns.
Social clusters.
Kei blinked.
"You're literally writing about the class."
"Yes."
Kei laughed softly.
"You weren't kidding about the experiment thing."
"No."
Kei pulled a chair beside Rei and sat down.
"So what's today's observation?"
Rei glanced briefly around the classroom.
"Heightened anxiety."
Kei followed her gaze.
Several students were indeed acting differently.
Whispering more.
Watching Yamauchi.
Watching Rei.
"Everyone's nervous about the test," Kei said.
"Yes."
"But you're not."
"No."
Kei leaned closer.
"You're really confident."
"That isn't confidence."
"Then what is it?"
Rei closed the notebook slowly.
"Preparation."
Kei studied her expression carefully.
Then she smiled slightly.
"You're enjoying this more than you admit."
Rei didn't respond.
But Kei's guess wasn't entirely incorrect.
Observation under pressure produced the most valuable results.
And the class was finally beginning to fracture.
The first period passed slowly.
Students struggled to focus on the lecture.
Even the teacher noticed the unusual tension in the room.
Rei, however, continued writing.
Every movement mattered now.
Small alliances were forming.
Three students had started supporting Yamauchi openly.
Two others were defending Rei during conversations.
The rest of the class floated between curiosity and neutrality.
It was exactly the kind of structure pressure created.
And Rei had predicted it.
But there was still one reaction she had not fully mapped.
Kei.
During the mid-morning break, Kei remained beside Rei's desk instead of returning to her seat.
"You know something?" Kei said quietly.
"What?"
"I think you're changing the class."
"That process had already begun."
"No," Kei said.
"You accelerated it."
Rei tilted her head slightly.
"That appears to be the current interpretation."
Kei watched her for several seconds.
Then she asked something unexpected.
"Did the White Room teach you to do this?"
The question landed quietly between them.
Rei's pen stopped moving.
Across the classroom, a few students continued talking, unaware of the conversation.
Rei looked up slowly.
"Why did you mention that?"
Kei shrugged lightly.
"I've heard rumors."
"From where?"
"Online forums. Discussions about elite training programs."
Rei studied her expression carefully.
Kei did not look accusatory.
Just curious.
"You're asking if those rumors are real," Rei said.
"Yes."
Rei closed her notebook.
Then she answered calmly.
"Some environments prioritize efficiency."
Kei frowned slightly.
"That's not really an answer."
"No."
Kei leaned closer.
"Were you trained somewhere like that?"
Rei held her gaze for several seconds.
Then she spoke quietly.
"I was trained to observe."
Kei felt a small chill run down her spine.
Not fear.
But the realization that Rei might not be exaggerating about her background.
"You really are dangerous," Kei murmured.
Rei didn't deny it.
Across the room, Horikita had noticed the shift in conversation.
She couldn't hear the exact words.
But Kei's expression told her enough.
Curiosity mixed with unease.
Horikita stood and walked toward them.
"Are we discussing secrets now?" she asked calmly.
Kei jumped slightly.
Horikita's timing had been perfect.
Rei looked up.
"Just speculation."
Horikita folded her arms.
"I doubt that."
Kei glanced between them.
"You two really don't like each other, huh?"
"That assumption is incorrect," Horikita replied.
"I simply prefer clarity."
Rei nodded slightly.
"A reasonable preference."
Horikita's eyes sharpened.
"Then allow me to ask something clearly."
Rei waited.
"Why are you really in Class D?"
The classroom quieted slightly.
Several nearby students were listening now.
Rei answered calmly.
"Because the school placed me here."
"That isn't an explanation."
"It is a fact."
Horikita studied her expression.
Searching for a flaw.
But Rei's tone remained completely steady.
Finally, Horikita spoke again.
"You're hiding something."
Rei tilted her head slightly.
"Everyone hides something."
Kei burst out laughing.
"You two are impossible."
Lunch arrived with even greater tension than the previous days.
The upcoming test was now only a short time away.
Students discussed strategies openly.
Yamauchi sat with his group of supporters.
Rei sat at her usual table.
And Kei joined her again.
But today she didn't speak immediately.
Instead, she studied Rei quietly.
"What?" Rei asked eventually.
Kei leaned forward slightly.
"I'm trying to figure something out."
"What?"
"You don't act like someone trying to win."
Rei raised an eyebrow.
"No?"
"No."
Kei tapped the table lightly.
"You act like someone running an experiment."
"That interpretation is accurate."
Kei sighed.
"So the test doesn't matter to you."
"It does."
"How?"
"It will produce results."
Kei laughed softly.
"You really are unbelievable."
Rei tilted her head.
"That reaction appears frequently."
Kei leaned closer again.
"You know what the weirdest part is?"
"What?"
"I think I'm starting to enjoy this."
Rei paused.
That response carried genuine honesty.
And it confirmed something she had begun suspecting.
Kei was not simply observing the experiment.
She was becoming part of it willingly.
That made her the most unusual variable in the entire system.
Later that afternoon, as the final class ended, Yamauchi approached Rei again.
But this time he wasn't angry.
He looked determined.
"I'm going to win," he said.
Rei looked up.
"That outcome remains possible."
Yamauchi frowned.
"You still talk like you've already calculated everything."
Rei stood calmly.
"I calculated probabilities."
"And mine?"
"Low."
Yamauchi clenched his fists slightly.
Then he turned and walked away.
Across the classroom, several students watched the interaction carefully.
The tension had reached a new level.
Because now the entire class was waiting for one moment.
The test.
And the result would determine more than just a score.
It would determine who controlled the narrative inside Class D.
As Rei left the school building that evening, Kei walked beside her again.
"You know," Kei said thoughtfully, "if you win that test, everything in the class is going to change."
"Yes."
"And if you lose?"
Rei looked at her.
"Then the experiment will become even more interesting."
Kei laughed.
"You're unbelievable."
Rei didn't disagree.
Because the truth was simple.
The class believed the test would decide the outcome of the conflict.
But Rei already understood something they didn't.
The outcome had been shaping the class for days.
And the real results had nothing to do with scores.