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English
Series:
Part 1 of Their Unsolvable Equations of Life
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Published:
2025-12-19
Updated:
2026-01-06
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145,527
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30/?
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Unsolvable Equation of Life

Chapter 3: First Day of School

Notes:

(See the end of the chapter for notes.)

Chapter Text

At first, nothing was wrong and everything was fine.

It was a beautiful spring morning. 

The sun had only just risen, painting the sky in soft hues of orange, thin clouds drifting lazily above. The air was cool and clean, carrying the delicate scent of blooming sakura petals that lingered with every breath she took.

She woke early and arrived at school among the very first students. First impressions mattered most, and today, she had to be flawless. Appearance, demeanour, speech, presentation—every detail had to be perfect.

She expected nothing less from herself. The Fujiwaras wouldn’t accept anything less from their pride.

Then something went wrong.

Sanae prided herself on her impeccable sense of direction. She had never once gotten lost within the Fujiwara domain, a place as vast as U.A.’s hill itself. One glance at the school map had been more than enough.

The first wrong turn didn’t concern her. Neither did the second.

But then another followed. And another.

After ten full minutes of looping through corridors that seemed to stretch endlessly, she finally had to admit it—painfully, reluctantly.

She was completely, absolutely, undeniably lost.

She retraced her steps through the empty halls, footsteps echoing softly as she tried to reconstruct the map she had memorized back at the entrance.

“I looked at the map… And I turned right like it showed. So how did I get lost?”

Should she return to the entrance and check again? Or continue forward for what felt like the fifth time in the last few minutes?

She closed her eyes and sighed softly, picking up her pace and preparing to turn yet another corner—

And bumped straight into someone. Her body pitched forward, balance slipping away.

“Ah—!” A small gasp left her mouth as her eyes flew open.

Before she could react—before she could even attempt to catch herself—an arm wrapped securely around her waist, stopping her fall. Another hand steadied her shoulder.

Her breath caught.

She looked up instinctively and found herself staring straight into a pair of crimson eyes.

Sharp. Intense. Glowing like embers at the edge of a dying fire. She had never seen a color so striking. There was heat in his gaze,something that made her chest tighten without warning.

And his face—

Strong features, sharp lines, a slight furrow of confusion.

A boy who was undeniably handsome.

He was holding her close. Close enough that she could feel the warmth of his hand through her uniform, the faint brush of his breath against her face, the lingering sakura scent still hanging in the air. His grip was gentle, steady, warm—

Sanae’s fluttered heart skipped a beat.

Then the realization hit—that someone was touching her like this—and in less than a fraction of a second, instinct took over. Her body moved before her mind could catch up.

Just like her training with Zhuo Fan, her martial arts teacher, in one swift, practiced motion, she grabbed his shoulder, pivoted, and pinned him against the wall. Hard enough to restrain. Gentle enough not to hurt.

“…the hell!?” He gasped in surprise.

She blinked, horror crashing over her all at once. He stared at her with wide, shocked eyes.
Her breath hitched, stepping back instantly. 

“I—I’m so sorry! I thought—my reflex—I didn’t mean to— !”

She bowed repeatedly, mortified.

She had only meant to defend herself—even if she hadn’t known what she was defending herself from—but she had just attacked another student on her very first day.

“So much for the expected perfection…” she thought to herself, cheeks burning. “What a terrible start…”

She dared to glance up.

He wasn’t angry.

He looked confused—slightly dazed—with a faint flush spreading across his cheeks.

“... It’s fine,” he said, sounding strangely gentle for someone she had more or less assaulted. “Don’t worry about it.”

His voice was deep and rough, yet unexpectedly warm. The tone caught her off guard, easing the tension in her chest.

She lifted her head and smiled brightly, gentle eyes meeting his.

“Ohh- Thank you,” She felt relief wash through her. “I didn’t hurt you…?”

“Tch, I’m fine.” he muttered. “Watch where you are going next time.”

“Of course!” she said, bowing once more. “I truly am sorry.”

She hurried away, embarrassment still clinging to her.

Yet her mind betrayed her, replaying the moment she had looked into his eyes.

And the way his arm had wrapped around her waist.

“Shut it Sanae, focus.” She told herself, shaking her head as if to wake up from the scene she’d just lived through.

—---

To her surprise, Sanae wasn’t the only one who stopped in front of the large classroom door, the bold lettering 1-A clearly displayed across it. The blond boy with crimson eyes—the same one she had collided with earlier—halted beside her. Judging by the brief look that crossed his face when he noticed her, he hadn’t expected this either.

“It seems like we belong to the same class.” she said, trying to break the awkward silence that settled between them.

It was rather disgraceful, really, to collide with a classmate on the very first day of school. Nee-san would’ve laughed at her.

“Tch.”

That was all he offered in response. He wore what looked like an irritated expression as he pushed the door open and stepped into the classroom. Maybe he truly was angry. After all, he had caught her from falling—and she had repaid him by pinning him against a wall.

Not exactly the best way to start a day.

Sanae followed him inside and quietly chose a seat in the middle of the row farthest from the teacher’s desk. She had never been fond of the front rows.

Students continued to trickle in, gradually filling the room, and she observed each of them with quiet interest. She had rarely interacted with people her own age—aside from her many cousins during family gatherings or formal occasions—so this was all new to her.

Several classmates stood out almost immediately.

First, obviously, was the blond boy she had met earlier. The memory alone made her feel faintly embarrassed all over again. He was leaning back in his seat with his feet propped up on the desk, and she found herself wondering if that was even allowed.

Nearby, a girl with pink skin chatted cheerfully with a red-haired boy.

A boy with dual-colored hair, a burn scar, and a perpetually gloomy expression took the seat beside her.

Another student had the head of a black bird. She found herself thinking—somewhat unexpectedly—that it was kind of cute.

Then there was an invisible girl. Quite literally invisible. Only her uniform gave away her presence; without it, Sanae wouldn’t have known she was there at all. The thought sent a small shiver down her spine.

A very short boy with grape-like hair sat a few rows away and had been staring at her for some time now. The attention felt… unsettling, creepy. Sanae made a mental note to be careful around him.

Two hybrid boys entered together—one with a large tail, the other with many arms spread like wings. They already seemed friendly with each other.

As she took it all in, she came to the conclusion that the list could go on forever. Every student in the class was unique in their own way.

Just then, a tall boy with glasses—who looked every bit the model student—approached the blond boy and firmly told him to put his feet down, as it was against the rules.

“So she was right,” she thought quietly. “It isn’t allowed”

The blond boy snapped almost immediately, yelling at the bespectacled student and calling him “extra” or something along those lines. She didn’t quite grasp the meaning, but she was certain it wasn’t meant kindly. It was hard to believe this was the same boy who had caught her in the corridor barely half an hour ago.

More students filtered into the room until, at last, the teacher arrived.

He introduced himself as Aizawa Shota—and appeared to be wrapped in a bright yellow sleeping bag.

Sanae very much wanted to ask why.

She never got the chance. The man looked utterly done with everything and went straight to the point. One of the first things he ordered was for them to change into their gym clothes and meet him in the gym.

Once everyone had assembled, Aizawa announced that they would be having a test—right here and now. It consisted of several physical exercises that, apparently, every middle school student had already done before. Judging by the lack of surprise among her classmates, she concluded she was likely the only one unfamiliar with it.

“Fujiwara.” he called once his explanation ended.

“Yes.” she replied, stepping forward.

“How far could you throw the ball in middle school?”

“Ah, I’m sorry, but I don’t know. I have always been homeschooled.”

She could feel the attention of the entire class turn toward her. The realization made her cheeks warm—it was embarrassing to be the only one in this situation.

“Oh—that’s right. Sorry about that, I forgot.” The teacher looked momentarily embarrassed. “Then Bakugou, what about you?”

She recognized the blond boy as he stepped forward. Bakugou. She made a mental note to ask people’s names more often instead of labeling them by appearance or hair color—it was rather rude when she thought about it.

Aizawa instructed Bakugou to throw the ball as far as he could. The boy wasted no time.

Sanae’s eardrums were assaulted by a shouted “DIE!” followed by a loud explosion.

“He certainly is passionate.” She thought with faint amusement.

Aizawa announced a remarkably high score, and Bakugou looked visibly pleased with himself. As attention shifted away, Sanae began calculating mass and vectors in her head—how she would optimize the throw—when Aizawa announced that the first test would be the 50-meter dash.

Virtual mass: reduced by 50%. Inertia adjustment: 5% lower.

She stepped forward.

In the following fraction of a second—

Vector control: no change in angle. Double the initial force.

“3.10 seconds, Fujiwara. Nice quirk control.”

Perhaps she should have reduced the inertia even further. Then again, that might have sent her flying and failing to demonstrate perfect mastery over her quirk would not reflect well on her.

“Thank you, sensei.” she replied cheerfully.

Among her classmates, the one with glasses—called Iida—seemed almost built for this test. He even surpassed her time. She winced at the mere 0.02-second difference and thought she truly should have lowered the inertia more or increased the vector force. Bakugou and the dual-haired boy, Todoroki, also performed well, impressive for quirks not suited to speed. Both of them were clearly strong.

The second test was grip strength. Once again, she passed with ease. It was far simpler than the dash—she merely had to lighten the object, cancel Earth’s gravitational pull on it, and triple the virtual mass of her hand.

“Well, this might be a new record for this particular test.” Aizawa remarked, sounding almost impressed. For someone who seemed so perpetually unmotivated, that alone was noteworthy.

“Fujiwara-san, isn’t it? That’s incredible!” a black-haired girl said, smiling warmly at her.

“Thank you, Yao—”

Ah. This was bad. She couldn’t remember the rest of her name.

“I’m Yaoyorozu Momo.”

“Thank you, Yaoyorozu-san.” She replied with a smile of her own.

The third and fourth tests involved jumping. Sanae claimed first place in both. By now, she had everyone’s attention—much like Bakugou and Todoroki, who also excelled in several of the trials.

The fifth test’s record belonged to the girl with the zero gravity quirk. She achieved an infinite score, as the ball never fell until she decided it should. Beating that would be difficult. Sanae settled for a comfortable second place by increasing the vector force just enough to send the ball flying clear over the school hill.

The green-haired boy, Midoriya Izuku, was particularly interesting to watch.

Especially when, during his turn, Sensei casually announced that the lowest-ranked student at the end of the day would be expelled. She wasn’t worried about herself, but the horrified faces of some other students shifted the mood to something heavier.

Midoriya’s quirk appeared incredibly powerful, yet he seemed unable to control it. He had to break a finger just to activate it. That was likely why she hadn’t seen him use his quirk during the previous tests. Did he also rely on calculations and simply get them wrong? She couldn’t tell.

Bakugou suddenly started yelling at him, repeatedly calling him “Deku.”

That was… really not a nice nickname.

Worse still, the angry blond began advancing toward Midoriya with very clear hostile intent. Anyone could see how terrified Midoriya was.

Is this bullying?

Her family had always told her that if she were ever bullied—if other students were being cruel—she should immediately report it to a teacher. She had never attended school before U.A., so she lacked experience, but she was certain of one thing: whatever Bakugou was doing to Midoriya right now wasn’t right.

She was about to step in and stop him.

Before she could, their teacher reacted first, restraining Bakugou with his capture weapon—endlessly long white bandages. Bakugou looked as though he’d seen a ghost when Midoriya used his quirk. The two clearly knew each other—most likely from the same middle school.

So why weren’t they friends?

She knew neither of them so it wasn’t her place to ask. There were still tests left to complete.

The final three trials were endurance running, the seated toe touch, and upper-body training. Sanae didn’t place first in the endurance run, though her ranking wasn’t low either. Endurance had always been something she needed to work on, so it wasn’t surprising. However, she secured first place easily in the remaining two tests.

Unsurprisingly, given her consistently high placements, she finished at the top of the leaderboard. Yaoyorozu, Todoroki, and Bakugou followed, in that order. Midoriya was ranked last.

The devastated expression on his face made her chest ache.

That feeling lasted less than a minute.

Aizawa quickly revealed that it had all been a bluff—no one was being expelled. She couldn’t help but wonder what the point of frightening the weaker students like that had been.

As she headed toward the school gates, preparing to go home, Yaoyorozu caught up with her.

“Fujiwara-san, you were so impressive today.”

“Thank you. You were impressive as well, Yaoyorozu-san.”

“Well, I have to train my body quite hard. My quirk doesn’t help much with hand-to-hand combat,” she admitted, looking slightly embarrassed. “Yours seems very strong for that, though. What exactly is it?”

“It’s Phenomenon Control. I can alter anything related to physical laws, as long as I understand them.”

“Wow… that sounds incredibly powerful.” Her eyes widened with genuine admiration. “Mine is Creation. I can create anything as long as I understand its composition.”

That sounded both amazing and endlessly versatile.

“That’s a wonderful quirk with so many applications. It’s somewhat similar to mine, isn’t it? You also need a deep understanding of what you’re doing.” Sanae said cheerfully.

The compliment made Yaoyorozu flush, clearly pleased. They walked together until they reached the bottom of the hill, where a luxurious car awaited her.

“Fujiwara-san… would you like us to be friends?”

“Huh?”

Her family had encouraged her to make friends if she ever attended school. Nee-san had often said it was a shame she never had the chance to meet new people and make friends. After her parents’ death, the Fujiwara family had guarded her like a precious treasure, afraid the murderer might come after her too.

It wasn’t that she had no one. She got along well with her cousins; they had played together often when she was younger.

But they were family.

And since she rarely left home…

Did that mean she truly didn’t have any friends?

That realization felt strangely heavy.

“Ah—sorry, it’s okay if you don’t want to,” Yaoyorozu said quickly, flustered. “I just thought that since you were homeschooled, it might be nice to stick together.”

“You were homeschooled too?”

“Yes.”

This was the part where she was supposed to say something reassuring, wasn’t it?

“Oh, you misunderstood. I wasn’t thinking of refusing,” Sanae said quickly, scratching the back of her head in embarrassment. “It’s just… no one has ever asked me to be friends before, so I was surprised. Of course I’d like to be friends with you.”

“That’s wonderful!” Yaoyorozu clasped her hands together, eyes shining. “I should be going now. See you tomorrow, Fujiwara-san.”

They waved goodbye, and Sanae continued on her way.

Before heading home, she stopped by a nearby park and began her own personal training. She chose a secluded field, far from people—she didn’t want to raise anyone’s alarm while testing her quirk.

Today had been eventful and she had even made her first friend.

Nee-san would be proud.

Notes:

This was the moment when I decided to go back rereading the entire manga, trying to closely follow the canon. Most of the story will follow the canon. Obviously, there's some changes here and there but it's far from my goal to make Sanae the main character of MHA.