- Lee Soo Yeon -

A certified genius, attending one of Seoul's top universities on a full scholarship. No parents and a chronically ill little brother in the hospital. Enter, numerous part-time jobs and almost daily visits to the hospital. The young, expressionless genius can't keep going forever, though, and it's only a matter of time before it gets to be too much and she needs a sick day. 

- Bang Sung Joon - 

Lee Soo Yeon's boyfriend. There was something about the stoic genius girl in his class that intrigued him. And once he cracked past that serious facade, he realized he found someone he enjoys being around and really cares for. But he's still the somewhat selfish, impatient boy he was when he first met her, and his interest has never held for long. 

- Jang Hyemi -

Soo Yeon's roommate and good friend. It's safe to say Soo Yeon's never had a best friend, but Hyemi definitely comes closest. A constant support and giver of cheer, she is to Soo Yeon an unexpected confidante and aide. 

- Chang Yoonhee - 

One of the more popular students in Soo Yeon's year, she's after another popular student as well--Soo Yeon's boyfriend. Until now she hasn't had much success, but progress is progress, and she'll take it even if it's as little as going from not talking to stepping out for coffee together once in a while.  

And then there's Kris. 

- Kris Wu - 

Kris has also been attracted to Soo Yeon. He's quiet as well, but not to the point where he's as expressionless and detached as she is. He's another one of the handful of people Soo Yeon's come to let into her life. He seems to always show up when she least expects, and now she's come to expect it. She may not always be in the mood, but he knows how to get her to open up. And whether she's noticed it or not, she's been changing little by little.