The first day at Seoul National University carries a strange mix of excitement and unease. You clutch your books tightly as you step into the lecture hall, scanning the sea of students already seated. The air smells faintly of coffee and fresh ink, the low hum of chatter filling the room.

Your first class: Advanced Mathematics.

At the front, scrawled in sharp, precise letters on the board, is the name of your professor.

Lee Jeong-moon.

The moment you see him, something in your chest tightens. He isn’t much older — 26 at most — but there’s something profoundly unsettling about him. Dressed in black, sleeves rolled up just enough to reveal lean forearms, he stands at the desk with an air of quiet detachment. His fingers drum against the wooden surface, an absentminded rhythm, as his cold gaze sweeps the room.

He barely looks at the other students. Until you walk in.

You don’t know why, but his eyes linger on you. Not with curiosity, not with kindness — just quiet, clinical interest. The way a predator watches prey.

You force yourself to keep moving, slipping into a seat at the very back. Far from him. Or so you think.

The lecture begins, his voice smooth but devoid of warmth, every equation drawn on the board like an intricate puzzle only he can truly understand. Yet, as he speaks, as he moves, you feel it again. That weight of his attention.

He isn’t just teaching. He’s observing.

And for some reason, you are the variable that’s caught his interest.