• Sulli Choi as Goo Jae-hee 

She grew up in the USA and was touched when she saw Tae-joon in a high jump competition. In order to see him, she dressed up as a boy to transfer to all-boy Genie High School.

• Choi Min-ho as Kang Tae-joon

He is a high jump athlete who holds the best record in the World Junior Championship. He receives love from fangirls for his outstanding looks that match his national representative rank. He is dull and only says what he wants to, nor is he very interested in girls. After he injured himself and knew he'd still be disabled even if he recovered, he announced he wouldn't high jump any more. He later regains his lost laugher after meeting his roommate, Jae-hee.

• Lee Hyun-woo as Cha Eun-gyeol 

He is a charming soccer player who likes to joke and very active. He is the mood creator wherever he goes. Even though he has many people around him because of his outstanding skill and looks, he has never been in love. He initially was sure that he likes a girl, but when he realizes that he likes Jae-hee, who is dressing up as a boy, he gets completely confused.

• Kim Ji-won as Seol Han-na

She is a gymnast and daughter from a rich family without any shortcomings. Although she possesses a reckless personality, in front of Tae-joon she becomes a gentle lady.

Nie sume watak utama jerrr lahh ~ Nak tengok gmbr ? Ngeh , ngehh ~