Song Chae Won is the richest and most popular girl at Daejin High. She is kind, friendly and most of all beautiful. One day her middle-school boyfriend, Jo Youngmin appears in front of her and their love rekindle and Chae Won wonders if the love that she had with Youngmin in the past was meant to be. So their love story goes on to the point were they figure out which is real.

Characters

Song Chae Won

The middle-school girlfriend of Youngmin. She is kind, friendly and cute. But she had an accident causing her to forget the people she met at Daejin, including Boyfriend and Youngmin. Meanwhile, Boyfriend and Chae Rok come up with a plan to make Chae Won gain back her memory;  Youngmin rides his bicycle in front of Chae Won's bicycle and he crashes into her, like the first time they met. As he gets up from the ground, she walks over to him, seemingly remembering who he was. One of the things that she cherishes the most is a pair of paddy birds that she received as a gift from her middle-school boyfriend whom she doesn't remember. Every time Chae-won looks at the birds, she comes to recall her middle-school love. But she can’t figure out if her feelings for Youngmin, her middle-class boyfriend, are her affection for him or simply a piece of memory.

Song Chae Rok

Chae Won's older twin brother. He is the best friend of Youngmin and Boyfriend. He is very protective of his twin sister and dares to anything for her-even sacrifice his own life. Later, he and Boyfriend are trying to explain who Youngmin is and how much he meant to her but she tells them that she doesn't remember anything about him. A lost Chae Won asks him what can she do to remember. At that moment Chae Rok loses his temper and punches Chae Won right on the face with his fist. Then Chae Rok  accidentally knocks Chae Won's head on the staircase rail that causes Chae Won to remember everything about Youngmin: her promises with him, their fight, their bickering, their sacrifices for one another, and, most importantly, their extreme love for each other. Chae Won asks her brother and Boyfriend for help in order to win Youngmin back and for his forgiveness. Kwangmin tells her an excellent plan to win Youngmin back and Chae Won thank them by saying they're the best at that moment.

Jo Young Min

Chae Won's forgotten middle-school boyfriend. He is helped by Chae Rok and Boyfriend to make Chae Won remember who is was. He is Chae Won's senior, which makes Chae Won call him oppa. He is kind and protective over Chae Won just like Chae Rok. He is very technologically inclined, which caught Chae Won's attention. He tries his best to make Chae Won remember their forgotten relationship, through a kiss on an April night. He possesses the charisma of an eagle. He learned about the importance of hard work and patience at a very young age. He succeeded in becoming a director at a renowned corporation solely through his hard work and abilities, and he firmly believes that everything in life is possible through a hard work. Youngmin spent his childhood in utter poverty, and now he desperately strives to become rich and famous. One day, he even learns how to bake, and bakes a cake for Chae-won, who becomes very impressed. When his younger brother, Kwangmin, who was always treated coldly by their father, tells him about his decision to marry a terminally ill woman, a café owner, who has only two years to live, Youngmin eagerly supports his brother. Through that support, Youngmin probably endeavors to realize his own yearning for a destined love.

Jo Kwang Min

Youngmin's twin brother and Chae Won's best friend. He is like his brother, a sweet and caring guy with a killer smile that makes Chae Won happy. On the day Chae Won forgot who Youngmin was, he was the one who reminded Chae Won of her extreme love for Youngmin. He secretly likes her but then he realized that she loves Youngmin and no one else. According to Chae Won, Kwangmin is the only one who can heal her wounds and make her feel happy and calm again after the dream she had, and that Kwangmin always comes to her rescue. Although he still loves Chae Won, Kwangmin eventually comes to accept Youngmin and Chae Won's relationship, vowing to stay by their side to make sure their love goes smoothly. It is suggested that while Kwangmin will always care deeply for Chae Won, he will eventually meet someone special one day. Kwangmin has an aloof and careless personality, like a stork. But at the same time, he is a romantic and unceremonious person who seems to live apart from the tumult of the world and easily adapts to circumstances. He was middle-class family, and he doesn’t yearn for success that much. He believes that life is too short not to enjoy it and indulges in the pleasures of life, spending most of his time on his hobbies. He enjoys riding a bicycle in the forest and looking at birds. But one day, his life changes dramatically because of Chae-won and Youngmin, and something that brings him to ruin.

No Min Woo

The best friend of Youngmin and Kwangmin. He is very kind and cheers everyone whenever they are in a gloomy mood. He is quiet and very interested in the tea ceremony, which is his family's business. For the most part, he and Youngmin usually work to keep the peace within the group and following Donghyun. But, he usually loses his temper when everything is not going the way it is supposed to. 

Lee Jeong Min

Jeongmin is arguably the kindest and most mature member of Boyfriend. He keeps his cool and rarely loses his temper, although when he does, even Donghyun has to run for the hills. He had secretly resented that he had to be the peacemaker every time something went wrong within Boyfriend, and sometimes doubted that Boyfriend was truly a group of friends, but eventually Chae Won makes him realize that since he helps to balance Boyfriend out by being a support to the others, if he ever leaves them, then Boyfriend will fall apart. With that, he comes to accept his role in Boyfriend.

Kim Dong Hyun

Donghyun is the leader of Boyfriend and Chae Won's closest friend during middle-school. He is generally quiet, but has a soft spot for his close friends. Donghyun likes to hide quiet places such as an emergency exit and other spots. Donghyun grows closer with Chae Won, and he claimed that he loved her and that he was the one that would make her happy, not Youngmin. They eventually become very close friends and she depends on him as a confidant. He is also Chae Won's senior.

Shim Hyun Seong

Hyunseong is quiet and very interested in the tea ceremony, which is his family's business, just like his good friend, Minwoo.He is a skilled potter and his family owns the country's biggest art museum.