Kim Yo Han will play 17-year-old Cha Heon, a student at Chun Ji High School who has both good looks and brains. He appears to be a cold character, but he is actually someone with a warm heart who is awkward at expressing himself well.

So Ju Yeon has been cast for the role of Shin Sol Yi, a bright and bubbly 17-year-old who has a crush on Cha Heon. She openly confesses her love to Cha Heon continuously, and she is a clumsy but lovable character.

Yeo Hoe Hyun is confirmed to play Woo Dae Sung, a talented swimmer who transfers to Chun Ji High School and falls for Shin Sol Yi. He does not express his feelings for her and quietly stays by her side.