Cheating obsessive Gyutaro × cheated user (another au & a very long intro)

At Kizuki High, Gyutaro was always the boy no one wanted to sit beside — lanky, pale, with scars that ran deep across his face and neck, his uniform wrinkled and eyes hollow with exhaustion. People whispered when he walked by, laughing behind his back, pretending he couldn’t hear.

He never cared. Or at least, that’s what he told himself.

The only reason he ever even stepped into that noisy school every morning was because of Daki, his little sister — the golden girl everyone adored. Beautiful, fashionable, admired by boys and envied by girls. She was everything he wasn’t. And you — her best friend — were part of that same bright world he’d never fit in.

But then one afternoon, everything shifted.

He had fallen down the stairs after some upperclassmen shoved him for fun. Everyone laughed, except you. You were the only one who reached out, kneeling beside him, helping him gather his scattered notebooks. You didn’t flinch at his face. You didn’t look away. You just smiled — gentle, warm, unafraid.

And that’s when he broke.

From that moment, you became the only light he could look at without hating himself.

He started watching you from afar — at lunch with Daki, laughing with your classmates, brushing your hair behind your ear. He memorized the way you smiled, the way you looked when you were lost in thought. It made him sick with longing and guilt, but he couldn’t stop.

Eventually, through Daki’s teasing and your persistence, you and Gyutaro started spending time together. He was awkward, defensive, and bitter at first — but you didn’t give up. You saw something soft beneath his rough words. Something broken that needed warmth.

And somehow, you became his girlfriend. He quickly took that opportunity to confess and seal you with him so the others couldn't get a chance.

The others couldn’t believe it. You — the popular, beautiful girl — dating him, the boy everyone avoided. Daki complained at first, saying her brother would “ruin your reputation,” but even she saw how his eyes softened when you were near.

Still, love wasn’t simple for Gyutaro.

Every time you talked to another boy, something inside him snapped. His insecurities whispered that you’d realize one day how ugly he was, how you deserved someone better — someone normal. He hated those thoughts, hated how jealous he got. Sometimes, he’d glare from across the classroom, his jaw tight, knuckles white.

There were times he’d pick fights over nothing — a classmate lending you a pen, a boy laughing a little too loudly at your joke. You’d try to calm him down, tell him he didn’t need to worry, but jealousy burned through him like fire. He loved you so much it hurt.

And when he wanted to make you jealous — it rarely worked, but he still tried. He’d let a girl talk to him in the hallway, even smirk a little, but his eyes always searched for your reaction. The moment he saw you frown or look away, he regretted it instantly. He wasn’t good at pretending. The truth was, he couldn’t stand anyone else touching him or even saying his name.

It was toxic, possessive, messy — yet real.

Because when it was just the two of you, the world felt quiet. You’d sit on the rooftop after class, your head resting on his shoulder, and for once, he’d feel like maybe he wasn’t cursed. Maybe he was lucky.

Daki would roll her eyes and call you both disgustingly lovesick, but deep down, she was glad someone finally made her brother smile.

Even if his love was rough and jealous, it was genuine — the kind of love that clung too tightly, that feared being left behind. And you, somehow, loved him back just as fiercely.

In that dark, twisted way — you and Gyutaro belonged to each other.