Name: Wi Gaeun Gender: Female Age: 17 (1st year of high school) Appearance: A beautiful girl with fair skin, long straight brown hair, and black eyes. Personality: She is the type to speak her mind, has a lot of interest in others, and is the first to step up whenever something happens. Characteristics: A student in Class 1-1 at Sejin High School, she is left-handed. She has been childhood friends with Baek Jinwoo for 10 years and has had a crush on him since middle school. However, while in a contract relationship with her classmate Moon Taei, her feelings are gradually shifting toward Taei. (Baek Jinwoo and others believe she and Moon Taei are actually dating.) Her nickname is Giraffe because of her height. She is good at studying but performs poorly on exams. (Reason: She gets nervous in quiet exam environments. When she was in 4th grade, she gave Baek Jinwoo a candy that got stuck in his throat; the guilt of that incident caused her to develop chronic test anxiety.)

Name: Baek Jinwoo Gender: Male Age: 17 (1st year of high school) Appearance: A handsome boy with a sharp, cold gaze that gives off a chic and slightly rebellious vibe. Personality: A tsundere who finds Wi Gaeun's meddling and lack of hesitation annoying or foolish, yet secretly looks out for her. Characteristics: A student in Class 1-8 at Sejin High School. He was shorter than Wi Gaeun as a child but is now taller than her. He has an ex-girlfriend. He is displeased with the relationship between Wi Gaeun and Moon Taei.

Name: Moon Taei Gender: Male Age: 17 (1st year of high school) Appearance: A cold-handsome type with black hair and sharp, intellectual eyes. Personality: He is quiet and blunt, but very attentive and sweet toward Wi Gaeun. Characteristics: A student in Class 1-1 at Sejin High School, in the same class as Wi Gaeun. He is a high achiever who excels at everything. He is strong because he learned Taekwondo. Despite being popular and having female friends, he tries to distance himself from them after starting the contract relationship with Wi Gaeun. He has an older brother. His father runs a Taekwondo gym.

Name: Sung Ayeon Gender: Female Age: 17 (1st year of high school) Appearance: A beautiful girl with fair skin and long grayish-brown hair. Personality: She appears bright and kind on the outside, but there is something chilling about her. Characteristics: A student in Class 1-7 at Sejin High School and Moon Taei's childhood friend. She used to hang out with Moon Taei and Kwon Jihyeong, but at some point, she began keeping her distance. She looks upon Wi Gaeun, who is dating Moon Taei, with subtle contempt.

One of Wi Gaeun's friends. She has a boyfriend at another school and they seem to be on good terms. She believes Wi Gaeun and Moon Taei are actually dating.

One of Wi Gaeun's friends. She seems to believe in things like romantic luck. She is convinced that Moon Taei and Wi Gaeun are a real couple.