Soubu High School was divided into nine regular classes and one that stood apart from the rest—the prestigious International Education Class, Class 3-J.
Unlike the ordinary classes, where the students were distributed based on average deviation values, Class 3-J had a noticeably higher standard. Its average deviation was two to three points above the regulars, and most of its members were returnee students from overseas or those planning to pursue education abroad.
Since there was only one such class, there was no need for further divisions. Class 3-J had always been considered a symbol of elite status within Soubu. It was the kind of class whose very name carried weight, representing quality, achievement, and excellence. The students in this classroom were supposed to be the very image of discipline and brilliance.
And yet—seated neatly in her chair, Yukinoshita Yukino, the one who embodied excellence both in appearance and in academic performance, was secretly fiddling with her phone under her desk.
Yes, that Yukinoshita.
The perfect student, the teacher's darling, the living embodiment of Soubu's "model of elegance and grace." She was supposed to be the type who would never dream of breaking rules, let alone during the most important first day of the new school year. Yet here she was, thumbs typing away, breaking a taboo she would normally have looked down upon.
If the teacher at the podium discovered her, Yukinoshita knew she would be gravely disappointed. But for the first time, Yukino couldn't bring herself to care.
Why?
Because just a few minutes earlier, she had caught sight of a scene that pierced her like a thorn—Hikigaya Hachiman standing at the school gate, side by side with another girl. Not just any girl. A soft-spoken beauty with calm eyes and flowing hair: Kato Megumi. The way they walked together, chatting as if it was the most natural thing in the world, left Yukino feeling a twisting discomfort in her chest.
That image wouldn't leave her.
In the past, whenever Hikigaya-kun interacted with other girls—Yuigahama Yui, Isshiki Iroha, and others—Yukino had never experienced this suffocating unease. Perhaps annoyance, perhaps mild irritation, but not this… not this hollow, bitter pang.
But things had changed.
Ever since Yukino and Hikigaya had officially entered into a relationship—not just in name but in the truest, most vulnerable sense of "boyfriend and girlfriend"—her heart had become so much more sensitive. The idea of him being overly close with another woman now felt unbearable, like a storm cloud pressing down on her chest.
And so, even as the teacher's voice droned faintly in the background, Yukino's sharp gaze stayed glued to her phone screen, waiting.
Then—ding!
Her phone vibrated with a new message.
"Huh? You don't know her?"
Her brows, which had been furrowed tightly in suspicion, eased just a fraction. A faint sigh escaped her lips, one so subtle it would have gone unnoticed by anyone around her.
The message had come from Hikigaya himself, arriving right on time.
A few moments earlier, she had sent him a sharp text, demanding to know who the girl was. And now, Hikigaya was flooding her with rapid-fire replies, explaining everything in detail: how he had only met Kato that very morning, how he gave her a ride purely out of kindness, and how they weren't even acquaintances before today. He even stressed—typos included—that he had no connection to her whatsoever.
For Yukino, the frantic tone, the rushed keystrokes, and even the mistakes in spelling all painted a very satisfying picture: Hikigaya-kun was desperately trying to reassure her.
"Fufu… his panic is so obvious," Yukino whispered under her breath, her lips curving faintly.
Still, that faint warmth didn't fully erase her unease. Her suspicion wasn't so easily dissolved. She typed back quickly, masking her true relief with an icy tone.
"Yukinoshita: A few words alone cannot clear the suspicion. Tell me, are you still hiding something from me?"
Almost instantly came the reply:
"Hikigaya: No, I've already told you everything that just happened between Kato-san and me, in full detail."
She pressed on.
"Yukinoshita: You'd better recall carefully if there are any omissions."
A pause. Then:
"Hikigaya: ?"
On the other end, Hikigaya slumped over his desk, his heart heavy with despair.
Seriously, what had he done to deserve this? He and Kato weren't even friends. At best, they were classmates—though honestly, even that felt like a stretch. Fate had cursed him by seating them together, nothing more.
"Sigh… why did Yukinoshita's possessiveness level suddenly skyrocket after that incident?" he groaned inwardly. "Guess I'll have to start running away from women entirely at this rate. Social distancing: max level!"
He was about to type out another long, overly cautious explanation when—sniff sniff.
A faint fragrance reached his nose.
"…Huh? That smells really good."
Perfume? Definitely perfume. And not the cheap, overpowering kind either—this was refined, subtle, and dangerously alluring. But that raised a problem.
"Wait a sec, isn't this classroom filled with a bunch of dudes around me?" Hikigaya thought, bewildered.
Before he could puzzle it out further, his line of sight shifted upward.
And then he froze.
Right in front of him—looming dangerously close—were two massive, awe-inspiring, rhythmically swaying… peaks.
"H-How… how are Yukino's multiplied by ten?!" Hikigaya's brain blue-screened on the spot.
Before he could even avert his eyes, the source of this terrifying aura revealed herself: Kirisu Mafuyu, their brand-new homeroom teacher. And her sharp, frosty eyes were fixed squarely on Hikigaya, staring at him as though he were nothing more than disposable trash.
The air froze.
"Waaaah! She's gonna kill me!!"
Moments later, Hikigaya was dragged to the back of the classroom, forced to stand as punishment for "inattention."
Meanwhile—back in Class 3-J—Yukino sat waiting for Hikigaya's next reply. But when none came, her frown deepened, and her irritation began to flare.
"So he was hiding something! He knew her from middle school and didn't tell me!" she thought, her knuckles tightening around her phone. "Was it intentional? Or just careless? Either way… Hikigaya-kun, are you trying to cheat on me?!"
Before her anger could spiral further, however, a familiar, calm voice echoed in her mind.
"Host, you do realize you can check Hikigaya Hachiman's basic information, right? You'll see he has no interest in Kato-san at all."
"…What?" Yukino blinked, momentarily stunned. "You mean to tell me there's actually such a feature? And you're only mentioning this now?"
"The Host never asked," the system replied flatly.
Yukino: "…"
She took a deep breath. "Meow… Calm down, Yukino. Don't get angry at an inorganic being. Just… open it. Quickly."
Yukinoshita's sharp eyes lingered on the translucent data panel floating in her mind.
Name: Hikigaya Hachiman
Personality: Gentle, reclusive, overly self-conscious
Hidden Personality: Wife-protecting maniac
Relationship with Host: Couple
Affection for Host: 99 (Deeply in love)
Affection for Kato Megumi: -5/100 (Afraid)
Degeneracy Value: 0/100 (Strict with himself, unwavering loyalty)
Her gaze locked on those words—Wife-protecting maniac. The storm of jealousy and frustration that had been brewing inside her suddenly softened. For the first time since this morning, her lips curved in the faintest of smiles.
"Heh… you should've just said so earlier," Yukino whispered under her breath, her cheeks tinged with the slightest pink. "He clearly loves me so much, but he refuses to admit it outright. Stubborn as ever… Just like yesterday afternoon, when he wouldn't back down no matter how much I teased him."
Her eyes slid further down the panel until they reached the section labeled Affection for Kato Megumi: -5.
"Eh…?" Yukino tilted her head slightly, her long black hair brushing her shoulder. "Negative? Isn't favorability supposed to start at zero? If it's a negative value, then…"
Her mind clicked. It means he wishes this person would just disappear.
"…Ah. Hikigaya-kun actually dislikes Kato-san that much?"
She blinked, momentarily stunned. Then, slowly, her chest loosened, the tightness that had been suffocating her since the school gate finally easing. Her boyfriend wasn't hiding anything. In fact, he was repelled by the other girl. The thought warmed her more than she'd like to admit.
"Well then, it seems I misunderstood. Hikigaya-kun is still as reliable as always."
But before she could savor that reassurance, the System's flat, emotionless voice cut in like a splash of cold water.
Host, this is not entirely good news. Hikigaya Hachiman's low favorability means it's nearly impossible for him to build a connection with Kato Megumi. Without a connection, points cannot be earned.
"…What?" Yukino's relief instantly faltered. She pressed her lips into a thin line, unable to refute the logic. Her eyes shifted reluctantly to the final section of the panel.
"Degeneracy Value…? What exactly does that mean?"
The System answered without hesitation, its mechanical tone utterly serious.
"The Degeneracy Value reflects the degree of Hikigaya Hachiman's degeneracy. The higher the value, the easier it is for him to actively approach other women. At high levels, infidelity becomes second nature.
Scenarios such as 'Accidental Harem Formation,' 'Caught in 4K with the Childhood Friend,' and even 'Indirect Kiss via Creampuff' are all possible outcomes."
"…Excuse me, what?!" Yukino nearly dropped her phone in shock. "Caught in 4K—?! And what the hell is indirect kiss via creampuff supposed to mean?!"
Her face flushed crimson. Just moments ago she had been admiring Hikigaya-kun's steadfast loyalty, and now this absurd explanation threatened to break her brain.
She pressed her palms to her cheeks, forcing herself to breathe slowly. "Phew… calm down, Yukino. This isn't something I should get hung up on."
After a few seconds, she nodded firmly to herself. "Yes, yes. As long as his Degeneracy Value is at zero, Hikigaya-kun is strict with himself. He's a good man. That's all that matters!"
But the System wasn't done.
Host, please refrain from being secretly pleased. Hikigaya Hachiman's Degeneracy Value being so low is a problem. With it at zero, it will be extremely difficult for him to get close to other girls. Without that, favorability with Kato Megumi will remain negative. Without raising it, points cannot be earned. And without points… your boyfriend will die in three years.
Yukino froze. The warmth that had been bubbling in her chest turned to ice.
"…You…"
Her earlier joy shattered instantly. Though the misunderstanding with Hikigaya had been cleared, what the System demanded of her now was nothing less than cruel.
To protect their future, she would have to do the unthinkable.
Not only could she not allow Hikigaya to remain "strict with himself," she would have to encourage him—her boyfriend—to grow closer to other women. To flirt. To act in ways she herself could barely stomach.
"I-I'm his girlfriend! How could I possibly let him do something so terrible?!" Yukino buried her face in her hands, her voice muffled. "Ugh… I really can't take this anymore."
Her heart squeezed painfully. The Yukinoshita Yukino who was always so composed and cold in public now found herself utterly lost, cornered by circumstances beyond her control.
"For the sake of our future… for the sake of keeping Hikigaya-kun alive… am I really supposed to push him into the arms of other girls?"
She clenched her fists. It felt like betrayal just to think it.
And yet, the question gnawed at her.
At that moment, in her isolation and frustration, she couldn't help but whisper softly into the empty classroom:
"Hikigaya-kun… If it were you, faced with a problem like this… how would you solve it?"