Chapter 6: The Demon of Trigonometry

The classroom still buzzed from the earlier sparring matches, but Iruka had barely given them ten minutes of rest before clapping his hands.

"Alright, everyone! Break's over—back to class. Sparring is just one part of being a shinobi. You need brains as well as brawn."

Groans rippled through the students. Even Kiba flopped over his desk like he'd just run a marathon.

"Today," Iruka continued, "we're revisiting kunai trajectory mathematics. Take out your notebook. Let's see how many of you actually studied over the break."

Naruto blinked. Math? Already?

He glanced at the chalkboard where Iruka began writing terms like angle of throw, arc radius, and crosswind compensation. It took exactly two seconds for realization to dawn on him.

"…Wait. This is trigonometry," he muttered.

Not that he'd seen any labels like sine, cosine, or tangent—but the logic was unmistakable. Trajectories, distances, angles, angles within triangles. It was all there, hidden beneath ninja-themed phrases like Kunai Path Curvature and Wind Chakra Correction Factor.

This is literally trig. Ninja trig.

He held his head in disbelief. "What the hell…"

Back in his past life, he'd tackled this stuff in college—and it wasn't even the fun kind. Just dry textbooks, one confusing equation after another. And now… these eleven-year-old kids were doing this like it was expected of them?

"I did this when I was seventeen… and they expect Kiba to do it at eleven?!"

Naruto glanced around the room. The moment the questions hit the board, half the class went white.

Kiba looked like he'd seen the Shinigami himself. Choji was gripping his pencil so hard it could be snapped in half. Even Shino's glasses were fogging.

Ino leaned over her notebook, biting her lip. She'd always been sharp, but even she was struggling to keep up with Iruka's rapid instructions.

Naruto exhaled slowly, leaned slightly toward her, and whispered, "Psst. Look—this part here, it's just a right-angle triangle problem. Use the bottom length and the angle to find the height."

Ino blinked. "Wha—how do you know that?"

He gave a sheepish grin. "Let's just say I had a really scary math teacher in another life. I hope you're proud of me, sir."

He helped her through the steps, hiding his hand behind his paper. No one noticed them, except Hinata, who peeked over her own notes and giggled quietly behind her sleeve.

But the moment Sakura raised her hand, everything took a sharp turn.

"Sensei!" she said, her voice chipper. "The answer is 2.5 shaku, and if you adjust for the wind, it becomes 2.86 shaku. That's page 112 of Fundamentals of Shinobi Geometry, second edition."

The room went silent.

Sakura hadn't even looked at her notes. She answered like the question was beneath her.

Kiba's mouth fell open.

Choji made a weak choking sound.

Even Iruka paused for a moment. "…Correct."

Sakura beamed. "I love this stuff. It's so easy."

That did it.

Naruto felt it rise up from the deepest parts of his soul. A primal urge.

"Take that witch away," he said aloud.

Or at least… he thought it was just in his head.

Until the entire classroom turned to him.

Naruto froze, eyes wide. "Wait. That was out loud?"

Kiba let out a bark of laughter, slamming his desk. "HAHA! He said it! He actually said it!"

Choji's shoulders were shaking with silent laughter. Shino's glasses flashed ominously, but even he was nodding.

Sasuke… Sasuke was just staring at Sakura like she was some kind of chakra-draining demon. He slowly turned to Naruto and gave a single nod.

A nod of agreement.

"Take her away," Sasuke said. "Please."

The boys erupted.

"Our hero!" Kiba declared dramatically.

"He's one of us!" another whispered from the back.

"This guy saved the class."

Naruto held his face in his hands, groaning. "This is worse than being punched."

Ino was gaping at him, slack-jawed, her pencil mid-air.

"Did you just call Sakura a witch?" she hissed.

"I didn't mean to!" Naruto hissed back. "It just… slipped out!"

But Ino's face was already turning red—not in anger, but from laughing too hard. She grabbed her mouth to stifle it, snorting into her sleeve. Even Hinata was giggling behind her notebook.

Sakura, meanwhile, was still frozen. Her smile had disappeared, replaced with a twitch in her left eye.

Iruka pinched the bridge of his nose. "Naruto…"

"Sorry, sensei! I swear it was an internal monologue!"

Iruka sighed, looked at Sakura's furious expression, then turned back to the chalkboard.

"Moving on…"

Naruto collapsed against his desk, face-down. He barely noticed Ino leaning closer.

"Hey," she whispered, amusement dancing in her voice, "I think you just declared war on Sakura."

"Please just bury me under math notes," Naruto mumbled.

She grinned. "At least teach me that triangle trick first."

He peeked up at her. "Still not free."

Ino squinted. "What?"

"Nothing," he said quickly, retreating before she could punch him.

From the corner of his eye, he caught Sasuke still staring at Sakura, then slowly shaking his head again, muttering under his breath.

It hit Naruto like a lightning bolt.

That's why he found her annoying in the anime.

Everything suddenly made sense.

The classroom settled into a tense silence, broken only by the soft scratching of pens and Sakura's page-flipping fury.

And in that moment, Naruto realized something important.

Sparring was one kind of battlefield.

But surviving ninja math?

That was war.