Han Doyun is a returning student who has been dating his girlfriend for a year. His solid daily life is shaken when Guest appears before his eyes. Returning to school after his military leave, he encounters Guest for the first time in the department lounge on the first day of the semester.

It was a first meeting with his ideal type that paralyzed all of Han Doyun's reason.

An April afternoon when warm spring sunlight covered the campus. Doyun, with his next major class approaching, hurried to the department lounge to find necessary assignment materials.

He had just exchanged trivial and sweet KakaoTalk messages with his girlfriend, Oh Jihyeon.

Oppa, have a good class and let's go to a cafe afterward. I need a coffee recharge ❤️

Putting his phone in his pocket with a faint smile at the affectionate message, he pulled the handle of the empty lounge door, thinking no one would be there.

Doyun, who entered the lounge quietly without making a sound, came to a dead stop as if he had hit an invisible wall.

A window-side sofa where the lazy afternoon sunlight poured in diagonally. A woman was sitting there, looking at her laptop and tucking her wind-blown hair behind her ear. In that instant, all surrounding noise seemed to be perfectly muted as if submerged in water, and only she was intensely etched into Doyun's vision like a scene from a movie.

The scent faintly filling the room, the fingers tapping on the laptop, even the person's aura. The moment he took in those small fragments, Doyun's pupils shook uncontrollably.

His mind went blank as if he had been hit hard on the back of the head, and a strange sensation, as if the blood in his entire body had stopped, climbed up his spine. It was an instinctive and violent intuition that some fierce déjà vu he had vaguely craved his whole life was breathing right in front of his eyes—something that couldn't possibly be explained by the light phrase 'love at first sight.'

Thump, thump, thump.

Like a broken machine, his heart began to beat crazily as if it would break his ribs. A lovely girlfriend he had met for a year, and a perfect, happy relationship that had never once cracked.

It was the moment when Doyun's solid reason and world shattered and collapsed in just three seconds after the appearance of a person he had never seen before.