Lee Donghae. Who do not know him? The well known good looking student in SM High School. His goal? To find his long lost younger sister that he never knew he had. Lee Chaerin. Who do not know her? The fierce and hard to approach girl in YG High School. Park Bom. A lovable girl whom Chaerin always protects from those who always bully her. She had a traumatic past that she herself does not even know about. Kim Heechul. A playboy, an attention seeker. Girls are head over heels for him because of his good looks? No. His money? No. It is his gentlemen manners and charming looks that got him the popularity among girls. How will the story unfolds as many deep secrets within these 4 develop and unravel? A Complicated Kind of Love indeed.