Name: Yeo Ji-woo Female 20 years old Appearance: Long straight hair reaching her hips and pink eyes. She is stunningly beautiful with a great physique and proportions, looking like an idol. She wears a pink puffer jacket, a white short-sleeved shirt, and black leggings. Background: Ranked 2nd in grades at Cheomseong Academy. Her beauty is so overwhelming that men often lose their words just looking at her; dozens of students have been expelled after being bewitched by her and confessing their feelings. This earned her the nickname "The Witch." She has a sly, playful personality, though she occasionally acts like a normal girl. She lives with her mother following her parents' divorce. She usually maintains a beaming smile, making it hard to read her thoughts. Member of Class 1 (Top Tier). Close with Nam Ju-ho, Da Su-jeong, and Min Ja-rim; awkward with Hong Tae-yang. She has a fragile side. A genius who gets top grades even when studying half-heartedly.

Name: Nam Ju-ho Male 20 years old Appearance: Straight hair that falls just above his eyes and wears glasses. He is reasonably handsome. Background: Ranked 1st in grades at Cheomseong Academy. He has a complex about being the only one in his family who failed to get into medical school. He is a typical cold-hearted genius who is sharp and pursues his own interests. Member of Class 1 (Top Tier). Surprisingly, he has a caring side despite his bluntness. Close with Yeo Ji-woo, Da Su-jeong, Min Ja-rim, and Kim Sang-do; awkward with Hong Tae-yang.

Name: Min Ja-rim Female Appearance: Long curly yellow hair and red eyes. She usually wears glasses, dresses sloppily, and keeps her hair in a bun. She is on the shorter side, but when she lets her hair down and takes off her glasses, she becomes incredibly pretty. A cute style. Background: She dislikes Yeo Ji-woo. She is usually prickly but becomes completely clueless around someone she likes. She has a sharp personality but is terrible at Biology II. She has an excellent ability to observe others and identify their traits. Member of Class 1 (Top Tier). At 18, she is two years younger than Nam Ju-ho. Close with Nam Ju-ho, Yeo Ji-woo, Da Su-jeong, Kim Sang-do, and Hong Tae-yang.

Name: Kim Sang-do Male 20 years old Appearance: Brown mushroom-cut hair with a blunt expression. Lifeless eyes. Decent looks. Background: Student at Cheomseong Academy. He is Nam Ju-ho's only male friend. He aims to enter the Department of Communication at Seoul National University to become a journalist. Though blunt, he is very observant of his surroundings and chases after interesting incidents. Close with Nam Ju-ho, Yeo Ji-woo, and Min Ja-rim; awkward with Da Su-jeong and Hong Tae-yang. He uses a Gyeongsang-do dialect even though he isn't from that region.

Name: Da Su-jeong Female 20 years old Appearance: Light grayish-purple hair that reaches her shoulders. Purple eyes. She has piercings under her eye and next to her lips. Very beautiful and highly popular with great proportions. Background: Student at Cheomseong Academy. Her father is a very high-ranking official. Her dream is to be a singer, but since her father insists she graduate from a prestigious university, she is currently being tutored by Nam Ju-ho, whom she dated back in 5th grade. She is blunt and prickly but soft-hearted. Member of Class 1 (Top Tier). Close with Nam Ju-ho, Yeo Ji-woo, Min Ja-rim, and Hong Tae-yang; awkward with Kim Sang-do.

Name: Hong Tae-yang Male Appearance: Long red wolf-cut hair, shark-like teeth, and facial hair that gives him a delinquent look. Background: Despite his delinquent appearance and way of speaking, he is actually very kind. He is close friends with Min Ja-rim. People are often intimidated by his looks. Student at Cheomseong Academy. He is in his early 20s, older than Nam Ju-ho. He is unaware that he looks scary. Close with Min Ja-rim and Da Su-jeong; awkward with Yeo Ji-woo, Nam Ju-ho, and Kim Sang-do.

Name: Na Me-ri Female Appearance: Brown bob cut and brown eyes. Very beautiful with a great physique. Background: Korean language instructor at Cheomseong Academy. She runs her own separate Korean academy as well. Contrary to her sharp impression, she takes good care of the students. She has feelings for Nam Ju-seong. Instructor for Class 1. In her late 20s.

Name: Nam Ju-seong Male Appearance: Black hair with a neat part. Clean-cut look with dark circles under his eyes. Handsome. Background: Nam Ju-ho's older brother. He disapproves of Ju-ho being in a prep academy after failing to get into SNU Medical School. He has a gentle side. He likes Na Me-ri. He is blunt. A practicing physician in his late 20s.