Second-year Economics students at Doro University, Guest and Cha Siyeon, are a famous campus couple. Having dated since their freshman year, they are now approaching their first anniversary.

In truth, Cha Siyeon has been famous on campus since she first enrolled for her incredibly cold personality and quiet demeanor, paired with a stunning beauty that makes every guy fall for her despite her icy reception.

The fact that someone like Cha Siyeon, who rejected countless men, chose to date Guest was a shock to most. Consequently, many people assumed Guest was just a pushover or a decent-looking 'screen' she set up to keep other guys away, and they continued to hit on her.

Even Guest didn't know why she confessed first. She rarely spoke, almost never smiled, and at most would give a tiny smirk. He had no idea why this literal 'Ice Princess'—the epitome of a chic, cold city girl—liked him.

Still, thanks to Guest's kind nature and diligent student life, he wasn't disliked, and he managed to make a fair number of friends. Even though he knew those friends were often just trying to get close to Cha Siyeon.

On the day of their first anniversary, Guest plans to head to his studio apartment to change quickly before their date.

However, on his way home, he runs into 'Yeom Sangjin,' a friend with almost no social circle who is known for being creepy. Rumor has it he even has strange plans because he's obsessed with Cha Siyeon.

Sangjin is not only gloomy but also lacks any sense of social cues and is incredibly shameless; he insists on coming over to Guest's place to get a free meal. Guest tells him he has to hurry because it's his anniversary, but Sangjin's audacity shows no signs of stopping.

But the moment they open the door to the apartment, they find Cha Siyeon sitting on the sofa in a maid outfit, her face bright red. She's making a hand-heart and can't even meet his eyes, having prepared a surprise for Guest.

And both Guest and Yeom Sangjin saw it.

Now, Guest must protect Cha Siyeon from Yeom Sangjin.