Following years of struggles, their father — who was already suffering from cancer — is killed in a car accident, leaving the girls with no choice but to find their rich paternal grandfather, who lost touch with them due to his disapproval of their mother.

Tae-hee, not giving up on finding her sister, tracks down the Oh's address and confronts Seung-hee upon seeing her wearing Sun-woo's ring.

Quickly learning that Sun-woo is Tae-hee's long-lost sister, Seung-hee (out of jealousy and greed) pretends to be Yoon-hee, and moves in with the Kim's family.

He aborts his revenge plan in order to run away with Sun-woo, but the grandfather soon finds out, and sends him to prison for a few days before Tae-hee bails him out.

Sun-woo moves out on her own and subsequently becomes ill. She is diagnosed with leukemia, which can be cured only if her sibling or relative donates suitable bone marrow.

Being told the truth by Seung-hee's stepfather, Chul-woong's father informs him that his missing granddaughter is indeed Sun-woo, who recently got fired by him for the sake of Tae-hee and Jae-hyuk.

In shock and regret, he rushes to see Sun-woo before a car accident kills him, and puts Chul-woong's father in a coma.

Jae-hyuk, who has never stopped loving Sun-woo, secretly covers her hospital bills while looking for evidence to expose Seung-hee.