In Korea, Ha-neul is a given a new name, Park Hae-won, and grows up in a wealthy, loving family, so much so that she finds it suffocating.

She secretly works at an aquarium and constantly gets into quarrels with the curator, Kang Dong-ha (Namkoong Min), who starts to like her.

She'd never forgotten him and like she'd imagined a million times in her dreams, her "real" brother has come back to get her, just as he'd promised.

Gun initially just wants to swindle money from Ha-neul, but he can't help protecting and caring for his little sister.

As the two grow closer, their relationship and feelings become more complicated, and they come to realize that their mutual affection is something more than that of a brother and a sister.