Young-sun, a 15-year-old girl abandoned by her foster parents with nowhere to go, stays at Sua's house as a tennis training partner. Young-sun tries to stay on Sua's good side, as well as her parents', so she can stay with the family. However, Sua, who was yearning for her parents' affection, becomes crossed by Young-sun's actions, and their conflict almost leads to Youngsun getting kicked out. Young-sun believes that Sua's mother will protect her as Sua's mother has been good to her the whole time, but when Sua's mother comes to believe that Young-sun is the cause of her family's conflict, she drives Young-sun out of the house herself. Upon returning to the orphanage, Young-sun despairs at the fact that she cannot have a family of her own despite all her efforts. However, Young-sun picks up the racket once again in the hopes to start her life anew.