Jin-Ho Myung (Kenichi Kando)Jin-Ho is a student in the final (senior) year of High School and finds himself a student in Hae-Young's class. Seemingly caring little for schoolwork, he has been known to go to the nurse's office to sleep, watch erotic movies in school, and complete mathematics tests (generally unsuccessfully) using pure guesswork. In middle school, it appears he was something of a delinquent who got into many fights, becoming quite skilled along the way. When it comes to his teachers, friends, or family he takes their physical abuse and in most cases takes the blame and punishments simply because he can (especially early on in the story). This has been a source of concern to his family, at the very least for his aunt who usually acts more like an older sister than a parent figure. However, he can also become focused if something interests him, like film, which caused him to be the co-founder and eventually the president of the school's Film Studies Club.He lives with his Aunt and father and there are suggestions in the story that he is estranged or separated from his mother, a possible cause for some of his more erratic behaviour.His sometimes rather cavalier attitude leads him into a number of compromising situations with his teacher. These instances have led Jin-Ho to fall in love with her.
Hae-Young Na (Elina Takanashi)A beautiful young woman in her mid-20's, Hae-Young teaches mathematics and also acts as the homeroom teacher for class 3-2, She lives with her sister and niece in an apartment block quite close to Jin-Ho. Her fatherâ€™s unexpected departure from her life when she was young has had a huge impact on her. Even though she is extremely attractive and was apparently popular (and pursued) throughout her school life, she has become very guarded around men, feeling unable to trust or form relationships with them. Consequently she is still a virgin and even shares her first kiss with Jin-Ho during the course of the story. She also seems to be following her mother's career path. She was also a teacher and became the district superintendent before retirement. There have been several instances where she acts rather childishly, in one instance taking her misplaced anger out on Jin-Ho. After being reminded of her absentee father by a news article, she slapped him repeatedly hard enough to give him a nose bleed because he didn't think he should apologize for a prior incident. Despite Hae-Young trying to be strict and meticulous in her work and home life, she has found herself in increasingly compromising and desperate situations with Jin-Ho. Much to her own initial displeasure and continuing discomfort, she finds herself developing romantic feelings for him, so much so that when they went on the MT trip, they kissed numerous times.At the end of volume 9, she finally admits to Jin-Ho that she does like him, even though it was a confession forced out of frustration towards Jin-Ho
Caroline Pendleton (Caroline Takanashi)She is a Eurasian (half Korean/half British) woman, recently arrived in Korea. She has lived in the United States for a while, learning the French martial art of savate. She has come to Korea because she is curious about her father's homeland and her siblings, who turn out to be Hae-Young and Hae-Jung. When she first arrives she lives temporarily at a motel while her father arranges for her to stay with her half-sisters for about a month. She has been employed as a language teacher and an assistant homeroom teacher under Hae-Young's supervision.Her first encounter with Jin-Ho, like her half-sister's, is not entirely without incident, ending in a fight and injury for her. Her opinion of Jin-ho changes, however, when he escorts her back to her motel room and shows concern for her well-being. As she has no full siblings she appears to harbour a strong desire for a warm relationship with her half-sisters, though this is complicated somewhat by their rather cold and distant relationship with their father. She expresses great romantic interest in Jin-Ho and has challenged Hae-Young to see who can win his heart (though it's not certain whether this is genuine or whether she just wants to bring the two together).
Young-Gi Cha (Hiro Hanai)Like Jin-Ho, he is a high-school senior, and is Jin-Ho's friend and classmate. They have been in placed together in the same class for the previous five years. Like his friend, he is skilled at fighting. It has been implied that he likes Ji-Soo; he is very protective of her and careful of how she perceives him. Young-Gi also has a strong sense of justice and, despite his tall athletic build, prefers to find the most peaceful resolutions to otherwise violent confrontations. His first encounter with Jin-Ho was back in middle school when Jin-Ho, a notable delinquent at the time, was fighting with another student; the two fought and soon afterwards became close friends.
Ji-Soo Ha (Mai Sugihara)She is the senior class president as well as now being the president of the student council. She is hardworking, studious, performs well and is also popular with both teachers and fellow students. She appears to have liked Jin-Ho ever since the freshmen year of high school, when he helped her make origami flowers. He does not feel the same way toward her, seeing her only as a friend. At one point, however, he does notice how attractive she has become and has saved her from being abused by other girls at school.
Ami Eun (Ami Nagumo)She is a senior and friend of Ji-Soo. She is shy and quiet at school, where she often reads yaoi manhwa. Often called "Monami" by Jin-Ho, a nickname to which she responds in a timid, albeit smiley way. Looks like everything's on its way for her to be one of many to fall under Jin-Ho's charms, right? WRONG! She befriends him and his closest friends because, like Jin-Ho, she has a crush on Hae-Young, and getting to know him is a way to find his weak spots to take him out. She eventually gets better...or not, because messing with Ji-Soo's thoughts for making her do an advance in his conquest for Jin-Ho's heart is something benefical to her plan of getting to Hae-Young. Or maybe she just wants to help Ji-Soo get rid of all those doubtful thoughts inside her head and encourage her to make a damn move for once.
Jae-Kyung Park (Akane Honda)She is a college freshman and a friend of Jin-Ho's. She was the co-founder and former president of the school film studies club, as well as being the former president of the student council. Even though she constantly flirts with him, Jin-Ho seems to feel comfortable enough with her to confide his girl problems to her. There are also hints that Jin-Ho may have had rather deeper feelings for her while she was in high school. It seems that Jin-Ho has been rather more distant with girls since she left.
Hae-Jung Nah (Marina Takanashi)Hae-Young's older (full) sister and roommate. She is, therefore, Caroline's half-sister too. Like Hae-Young, she has not forgiven her father for abandoning them as children, though she seems rather less bitter about it than her sister. She is the mother of a four-year old girl, Mi-Na Choi, and seems to be the most sensible of all the sisters. She also appears to have the closest relationship with their mother.
Ji-Sun Myung (Yuuko Kando)Jin-Ho's screen writer aunt who lives with him and his father. She often talks to (and looks out for) her nephew but is not afraid of hitting him when she thinks he has stepped out of line. She also acts to diffuse the sometimes explosive tension between Jin-Ho and his rather authoritarian and distant father, who in some cases beats Jin-Ho when he is displeased with him. One example of this occured when Jin-Ho arrived home after staying the night (at his teacher's house). His father beat him so badly he had to wear an eye patch to school.
Sung-Chul Nah (Kiyohiki Takanashi)Sung-Chul is father of Hae-Young, Hae-Jung and Caroline. A documentary film maker, he left his family to go to the United Kingdom, though there is some question as to whether he or his first wife initiated this separation. In the UK he fathered his third daughter, Caroline, with a British woman named Grace Pendleton. Even though his eldest daughters will not forgive his leaving them, he has asked them not to take out their frustrations and anger on their half-sister Carrie. For Hae-Young at least, this is proving to be a tall order.