Jin Song-ah

She has an outgoing and sunny personality. She’s an honest person.
She was born a few minutes before her twin sister and so she took on the mantle of the eldest child in her family. She would have to babysit for her siblings because her parents were always busy with work. In her family, she brought a smile to everyone’s faces. She contracted leukemia when she was 13 but a bone marrow transplant from her twin sister cured her.

With a lot of love for her family, Song-ah was especially close with her twin sister, Hyun-ah. Even when they grew older, she always slept in the same room with her.
Hyun-ah was Song-ah’s sister and soulmate while Senna was her best friend. Senna was the daughter of their live-in housemaid.

Kang Senna

Despite being poor and having a mother working at a minimum wage as a housekeeper, Senna is smart, pretty and attractive. Men will turn their heads and look at her.

Senna was taller, slimmer and prettier than the princess twins, but she wore hand-me-down clothes given to her by the twins so her clothes were always one size too small for her. When her classmates were invited to Song-ah’s house, they would tease Senna for wearing hand-me-downs that Song-ha gave her, but Senna would laughed it off with extraordinary composure and self-retraint.

Koo Kang-mo

He is just a middle manager overseeing the new business division in his father’s business and although he is out of the running to be the company CEO, this gives him more freedom and he has no hard feelings about it. He has a peculiar worldview.

Kang-mo’s nickname among the employees is invisible boss. He doesn’t appear at work on time and when he does, he’s hardly in his office. Chairman Koo turns a blind eyes to his son’s carefree lifestyle but Kang-min takes a stern position against his brother, Kang-mo for being so irresponsible.
But Kang-mo laughs in Kang-min’s face when his brother criticizes him. While he looks laid back all the time, Kang-mo is exceptionally smart. He is a genius who has a Mensa membership card and graduated from Harvard.

Koo Kang-min

Kang-mo’s stepbrother.
A classy gentleman who is good-looking. He is principled, rational, strategic and a perfectionist. Since his stepbrother Kang-mo is disinterested in running the company, Kang-min is confident that he will be named the successor to his father.

Kang-min turns down any arranged dates with daughters from prominent families but he had his eyes on Hyun-ah for a very long time. He was drawn to Hyun-ah, an alpha woman, who acted coolly with an understated charisma. While Kang-min was pursuing Hyun-ah, she had an accident at sea and died. This devastated Kang-min.

Cha Gun-woo

His mother died while giving birth to him and he lived in the servants’ wing at Chairman Koo’s mansion with his father. When his father died from cancer, Chairman Koo took in Gun-woo and raised him.

Gun-woo decided to call of his engagement with Song-ah and date Senna. But Gun-woo is later shocked to learn that Senna had used him to get revenge on Song-ah.