The teachers' office was still brightly lit at 8:30 PM.
Mashima Tomoya was flipping through an English dictionary.
As the homeroom teacher of Class A, he usually maintained a reserved demeanor in front of his students, keeping an appropriate distance from each of them.
But those who knew him well understood—this seemingly aloof teacher harbored genuine care for his students.
Before taking on a new class, he would always spend three full days meticulously reviewing every student's file, just to understand their individual traits faster.
And when it came to lesson planning? To ensure the quality of every lecture, he dedicated at least three hours daily to preparation.
If there were a "Most Dedicated Teacher of the Year" award for first-years—assuming no foul play—Mashima would undoubtedly take first place.
Mashima turned another page of his teaching notes, then glanced at his thermos. Empty.
He stood up to refill it with hot water.
But the moment he turned around—he froze.
The office, which should have been deserted at this hour, was completely occupied.
Hoshinomiya Chie (Class B) was bent over a stack of assignments, grading intently.
Sakagami Kazuma (Class C) leaned back in his chair, twirling a pen between his fingers.
Most surprising of all—Chabashira Sae (Class D) sat at her desk, tapping her fingers rhythmically against the surface.
Mashima instinctively checked the wall clock.
This wasn't normal.
At this time, the office should've been his private workspace. Occasionally, he'd run into Sakagami, but all four homeroom teachers present? That was unheard of.
His gaze lingered on Sakagami for a few extra seconds.
As colleagues, they maintained surface-level courtesy but never grew close.
Mashima could never approve of Sakagami's blind favoritism—no matter how his students acted, this teacher always took their side, even resorting to underhanded tactics behind the scenes.
Yet, Mashima had to admit—Sakagami prioritized his class's interests above all else.
This obsessive protection might stem from a teacher's sense of duty… or perhaps it was just about that lucrative year-end bonus tied to class performance.
But in the end, the reason didn't matter. Results did.
As for the other two—Hoshinomiya Chie and Chabashira Sae—they were old acquaintances.
The three had been classmates in high school, though in different sections. Now, by some twist of fate, they'd ended up working at the same school.
A strange kind of reunion.
But if Mashima were to give an honest evaluation as a friend—neither could be called a competent teacher.
Hoshinomiya's personal life was… chaotic.
She changed boyfriends more frequently than the class schedule.
Mashima didn't care to judge her choices, but the real issue? She'd sneak out to drink on weekdays, then stumble into class the next day with dark circles and alcohol clinging to her clothes.
How could anyone teach properly in that state?
Chabashira was the polar opposite.
Cold, detached—aside from that failed high-school romance, she hadn't dated in years.
Mashima suspected her ever-present cigarettes scared off most suitors. Not many men could tolerate a partner who reeked of tobacco.
Her teaching attitude? Even lazier than Hoshinomiya.
Arrived exactly on time, left the second class ended.
Never once successfully advanced her class.
More like a clock-punching office ghost than an educator.
That said… in terms of raw skill, they were no worse than him.
Otherwise, Highly Advanced Nurturing High School's strict hiring standards would've weeded them out long ago.
Mashima still remembered—Chabashira had once been a meticulous teacher.
Her lesson plans were detailed and neat.
She never missed after-class tutoring sessions.
But after "that incident", Hoshinomiya—like a shark scenting blood—began targeting her relentlessly.
The two classes' grades plummeted in their feud, eventually sinking to the bottom of the rankings.
Meanwhile, Mashima reaped the benefits, securing the Class A homeroom position year after year.
Yet whenever he saw the names of expelled students on those class rosters, he couldn't help but think—
The real casualties of this silent war were never the teachers… but the kids in those classrooms.
He'd tried advising them in private, multiple times.
But Chabashira consistently ranked last in annual evaluations, eventually getting demoted to Class D.
Over time, the once-meticulous Chabashira eroded into the apathetic shell she was now.
And Hoshinomiya? She hadn't started out this way either.
Back when they first joined the school, she'd graded papers late into the night—until Chabashira gave up entirely. Only then did she follow suit.
The unopened lesson plans in her desk drawers and the increasingly heavy perfume spoke volumes of her own resignation.
Mashima knew—if they were assigning blame for the past, Chabashira was at fault.
So now, watching Hoshinomiya hide her dark circles under mascara, he couldn't even scold her.
On weekends, when class rivalries weren't involved, the two would still go drinking together.
But once rankings were on the line? Those buried grudges resurfaced, suddenly more critical than final exam scores.
Back to the present.
The point was—he hadn't seen either of them this serious in years.
But starting to put in effort now? It was far too late.
"Class A will still be mine this month." Mashima stated matter-of-factly. "My students discovered the hidden rules within days of the term starting. To this day, they've lost less than 80 class points."
It wasn't unprecedented for students to uncover the rules.
But timing was everything—find them too late, and it meant nothing.
Even if discovered, keeping it from the class rendered it useless.
And getting an entire class to strictly follow school regulations? That was the hardest part.
These three hurdles filtered out 99% of students.
Yet his Class A had cleared them all flawlessly.
With leaders like Sakayanagi Arisu and Katsuragi Kōhei at the helm…
For the first time in his career, he felt certain of victory by the second week.
"Tch! Class A always starts strong and crashes hard. The real battle hasn't even begun!" Sakagami adjusted his glasses with a sneer.
"My, what a coincidence~ Our Class B just figured out the hidden rules too!" Hoshinomiya chirped, smiling sweetly.
"Wh— How?!" Sakagami's composure cracked.
If Class A uncovering the rules was expected… how did Class B manage it?!
Hoshinomiya merely giggled, turning to Chabashira. "Come on, Sae-chan~ No use pretending. Your Class D's already spread the word, right?"
Chabashira shot her a cold sidelong glance. "...You talk too much."
That single offhand remark made Sakagami's face pale.
Class D… knew too?!
Which meant—the only class still in the dark was Class C.
Because traditionally… A and B sat at one table, while C and D sat at another.