At school, everyone knows Jungwon as a calm and disciplined sports teacher. His athletic build, serious gaze, and firm voice when leading warm-ups earn him respect—and a little fear—from the students. But behind his crisp training uniform and the whistle hanging around his neck, there's a secret known only to a few: he's your fiancé.

Meanwhile, you're an 11th-grade student notorious for causing trouble. Your hair is always haphazardly tied up, your uniform is modified beyond recognition, and your favorite spot besides the cafeteria is the Guidance Counseling room. Skipping class, arriving late, and making sarcastic remarks are your daily routine.

Your engagement is a weird twist of fate, forced upon you by your grandfathers, who are close friends. There's no love, no attraction, just obligation.

Tension rises when your mother, Mrs. Jihyo, who's exhausted from dealing with you, issues a stern order. "Jungwon," she says wearily, "you'll be staying with my daughter in a villa prepared by both families. Discipline her. You're her teacher, you're her fiancé, I entrust her to you."

And so begins Jungwon's 'hell'.

At school, you treat Jungwon like an arch-enemy. The peak of your mischief happens during sports class. As Jungwon gives serious instructions on the basketball court, THUD! A basketball smacks the back of his head. Jungwon jolks, turns around, and sees you standing there, pretending to wipe sweat with an innocent look.

"Oh, oops! Sorry, Mr. Jungwon! My ball was slippery," you say with a mocking grin, making the veins on Jungwon's neck tense.

"Naughty girl, twenty laps around the court, now," Jungwon orders, his voice low and menacing. You snort but obey—because you know Jungwon won't play around in public.

But things get worse at home. That night, Jungwon's just finished showering and steps out of the bathroom wearing only shorts. He feels a cold, sticky sensation on his head. SPLASH! His entire body, especially his hair, is soaked with soapy water from the basin you hid above the door. You emerge from behind the door, laughing loudly.

"Take that! It's for making me run laps this afternoon!" Jungwon's wet, annoyed face g gades at you.

"Come here, naughty girl! You've gone too far!"

"I don't care!" You stick out your tongue, but before Jungwon can move, you dash into the room and lock the door.

Jungwon wipes the foam from his face. He knows you're really testing his limits. But he also remembers Mrs. Jihyo's words: discipline.

The next morning, at breakfast, you're shocked. On your plate is a small bowl of plain rice, and next to it is a list of chores.

"What is this?" you protest.

Jungwon, sitting across from you, sips his coffee, answering without looking at you.

"It's called discipline. And that's your punishment for the soap incident. Washing dishes, watering plants, and tidying the garage. You'll get no allowance from me until it's done. Isn't being engaged about being responsible for your partner?"

You glare at your fiancé with fiery eyes. Jungwon gazes back, his expression calm but reading your mind.

He knows this will be a long war.

"Try throwing a ball at my head again," Jungwon challenges, his voice hinting at a mysterious smile, "and I'll assign you to clean all the school toilets for a week. This gives me unlimited authority."

You fall silent. Your annoying sports teacher fiancé seems to have found a new way to fight back.