The agreement with Yamauchi changed the rhythm of Class D.
Rei noticed it the moment she entered the classroom the next morning.
The attention that had once been scattered was now focused.
Students did not pretend otherwise anymore.
They were openly watching her.
The reason was simple.
A challenge had been issued.
And challenges created narratives. Narratives created sides. Sides created tension.
Rei walked to her seat without acknowledging the attention.
The classroom felt louder than usual, yet strangely controlled. Conversations kept circling the same topic.
The upcoming test.
And Rei.
She sat down and opened her notebook as usual.
But before she could begin writing—
"You really did it."
Kei's voice came from beside her desk.
Rei looked up.
Kei was smiling again.
"You started a competition," Kei said.
"I accepted one," Rei corrected.
"Same thing."
Kei pulled a chair closer and sat across from her.
"You know everyone's talking about it, right?"
"That outcome was predictable."
Kei rested her chin on her hand.
"Does anything ever surprise you?"
Rei paused.
Then she answered honestly.
"Yes."
Kei's eyes brightened.
"Oh? Like what?"
Rei looked directly at her.
"Your reactions."
Kei blinked.
"Mine?"
"Yes."
"That's weird."
"Explain."
Kei thought for a moment.
"Well… most people would avoid someone who treats them like a science project."
Rei didn't answer.
Kei continued.
"But instead, I keep coming back."
Rei closed her notebook slowly.
"Yes."
"And you're curious why?"
"Yes."
Kei smiled.
"Because I want to see what happens next."
The answer carried genuine excitement.
Not fear.
Not hesitation.
Excitement.
Rei studied her for several seconds.
That reaction pattern was becoming clearer now.
Kei was not simply curious.
She was entertained by uncertainty.
That meant increasing pressure would likely draw her closer instead of pushing her away.
A rare psychological profile.
Interesting.
The first class began shortly afterward.
But the tension from the challenge continued spreading through the room.
Yamauchi looked unusually confident.
He had been telling anyone who would listen that Rei would fail.
Several students seemed convinced.
Others weren't sure.
But one thing was certain.
Everyone wanted to see the result.
Rei remained silent.
The teacher wrote equations across the board.
Students copied them.
But half the class kept glancing toward Rei.
Even Horikita.
Horikita's observation had become sharper in recent days.
She had noticed the pattern forming around Rei.
And she understood something most others did not.
Rei was not reacting to the class.
The class was reacting to her.
That difference mattered.
During the mid-morning break, Horikita finally approached Rei directly.
She stopped beside the desk.
"You're doing this intentionally."
Rei looked up calmly.
"Doing what?"
"Manipulating the atmosphere in this class."
Several nearby students immediately fell silent.
Rei considered the accusation.
Then she asked a question.
"Is the atmosphere uncomfortable?"
Horikita frowned.
"That isn't the point."
"Then what is?"
Horikita folded her arms.
"You're applying pressure to people."
"Yes."
The answer came without hesitation.
Horikita blinked.
"You're admitting it?"
"Yes."
"Why?"
Rei looked around the classroom briefly.
Then she answered.
"Because pressure reveals structure."
Horikita's eyes narrowed slightly.
"You're treating the class like a system."
"It is a system."
"And what role do you think you play in it?"
Rei paused.
Then she answered.
"Currently? A catalyst."
The word hung in the air.
Students exchanged glances.
Horikita studied her carefully.
Then she asked a final question.
"And what happens after the catalyst?"
Rei held her gaze.
"Reaction."
The lunch break that day felt different again.
Students filled the cafeteria with louder conversation than usual.
The challenge had become entertainment.
Several students even discussed placing bets on the outcome of the test.
Rei sat at the same table she always used.
Consistency.
Predictability.
Those elements made manipulation easier.
Kei arrived shortly afterward.
But today, she did something new.
Instead of sitting across from Rei—
She sat beside her.
The movement caught Rei's attention immediately.
"Testing proximity?" Rei asked.
Kei laughed softly.
"You noticed."
"Yes."
"Well?" Kei asked. "Does it change the experiment?"
Rei considered the new variable.
"Yes."
"How?"
"You're increasing the psychological pressure on yourself."
Kei leaned slightly closer.
"Am I?"
"Yes."
"And what happens if I keep doing it?"
Rei turned her head slightly toward her.
The distance between them had become noticeably smaller.
"Then the results will become clearer."
Kei smiled faintly.
"You talk about results a lot."
"They matter."
"And what result do you want from me?"
Rei studied her expression.
Then she answered honestly.
"Your genuine reaction."
Kei held her gaze for several seconds.
Then she whispered quietly—
"You might not like it."
Rei's reply was immediate.
"I rarely dislike data."
Across the cafeteria, Yamauchi was watching them.
And he didn't look happy.
The attention he expected to receive from the challenge was shifting.
Instead of focusing on him—
Students were watching Rei and Kei.
That irritated him.
"Look at them," one of his friends muttered.
Yamauchi clenched his jaw.
"She's just pretending to be smart."
But the confidence in his voice was weaker now.
Because Rei didn't look nervous.
Not at all.
And that made the challenge feel less like a game.
More like a mistake.
Later that afternoon, Kei and Rei walked through the hallway together after class.
Not intentionally.
It simply happened.
Their steps matched pace naturally.
"You know something?" Kei said.
"What?"
"You scare people."
Rei looked at her.
"That reaction is common."
"But you don't scare me."
"I know."
Kei smiled slightly.
"That disappoint you?"
"No."
Rei looked forward again.
"It complicates the experiment."
Kei laughed.
"Good."
They reached the staircase.
Students passed by them in small groups.
Some glanced at them.
Whispers followed.
Kei noticed.
"You've really changed the class."
Rei answered calmly.
"No."
She stepped onto the stairs.
"I only accelerated what was already there."
Kei followed beside her.
"And what was that?"
Rei paused briefly before answering.
"Competition."
Kei smiled again.
"And what about us?"
Rei looked at her for a moment.
Then she said something unexpected.
"We're not competing."
Kei raised an eyebrow.
"No?"
"No."
Rei continued walking.
"You're something else."
Kei tilted her head curiously.
"What kind of 'something'?"
Rei didn't answer immediately.
Because the truth was—
She hadn't fully determined that yet.
But the answer would come soon.
Pressure always produced results.
And the next stage of the experiment was approaching.