Soo Naeun is a high schooler of Seoul High School. She's to what they call her "Ms. Perfect". Why is that? Because beside from her perfect background, she's also one of the smartest kids in school. She has a bright and strong personality. 

The girl to which they call her "Ms. Perfect" also have a perfect boyfriend, Jung JinYoung, a.k.a "Mr. Perfect". As the smartest kid in school with a perfect background and an adorable face, he's the one that every girls would die to be his. But eventually he chose Naeun.

After 2 years of dating, their love was always the same. He was proud that she's a faithful girlfriend and she was proud that he's an awesome boyfriend. They lived up to many expectations but their love never change. Until...

Lee Jung Hwan, a.k.a Sandeul, an extremely outgoing guy transfered to Seoul high that turned  the school ranking up side down. He's a normal kid with a normal background but with his brain he captured everyone's attention. He has a bright personality and quiet frank. With his bright smile, he captured the ladies' hearts within the first glare.

Will Naeun be able stay faithful with the new guy's appearance?

What will happen? How does the story goes? Just keep on reading ^^