Yoon Seulbi, an average college students who enrolled to a major she doesn't like. Struggling enough with the new fresh college life, she's tangled between messed of 13 handsome young men who were as troubled even more than her in a Campus Festival Commmittee
 
  Choi Seungcheol - The Head of Taekwondo Club, majoring in Mechanical Engineering. The same year with Seulbi, someone who always dream to be a doctor actually
 
  Yoon Jeonghan - Seulbi's Twin btother, Majoring in Architecture. The sweet angel that has deepest darkest secret among all
 
  Hong Jisoo - Majoring in Environmental Engineering, the most gentleman among all who secretly experienced child abused
 
  Wen Junhui - Star of his department, Fine Arts. He's the prettiest flower any girls would dream off, but in package with poisonous thorn
 
  Kwon Soonyoung - The Jokester, same major with Seulbi, Civil Engineering. Just being around him make people laugh, but actually his pain is the biggest
 
  Jeon Wonwoo - The most talented writer but forced to major in Businesses as his family heir. Quiet and thoughtful
 
  Lee Jihoon - The baby by appearance, the boss by brain. Majoring in Computer Engineering
 
  Lee Seokmin - Ray ball of sunshine, bestie with Seulbi since in diapers. Majoring in Urban Planning
 
  Kim Mingyu - Arch enemy of Seungcheol, majoring in Electrical Engineering which also the enemy Seungcheols's department
 
  Xu Minghao - Majoring in Geology, the mysterious one
 
  Boo Seungkwan - The Diva of Science Department, can be mean sometimes but he's no harm
 
  Hansol Vernon Chwe - The hottie from Naval Architecture, dork and playful but has devious side
 
  Lee Chan - The real baby, sama major with Vernon