So-Yoon was born in the mountains, where her mother died giving birth to her. She was said to be found wrapped up in a bloody cloth, her mother's Rosary on her wrist. From a very young age, she could see spirits.Her Grandmother took her in and attempted to make her become a Medium, by "marrying a God" through a special ceremony. As a child, she was told that "marrying a God" was a good thing and it was a position that her family had honored more than anything, and that her mother would be proud.
However, So-Yoon disagreed since her mother - whose spirit still remained - told her otherwise, saying that she did not want her to become a Medium. As a result of becoming one, the ghosts around their house would be "cleared out, once and for all' and that the family would regain its former glory and honor, which her grandmother considered to be a noble act. So-Yoon was expected to dance in order to call out the God.
Regardless of her grandmother's wishes and words, So-Yoon decided not to become a Medium, much to the annoyance of her grandmother. During the ceremony, however, So-Yoon got into an accident with another girl, while still in her ceremonial clothes. This girl was later revealed to be Chae-Rim.
Sometime during her childhood, So-Yoon would gain protection from Banya, who would inform her of the result of her becoming a Medium, which made her believe that her mother didn't want her to become one for his sake.
A Rosary in the form of a bracelet is the only thing her mother left behind, which So-Yoon tries to keep safe in her possession, for it provides protection from wandering ghosts outside her house. In her opinion, Banya has wasted so much time protecting her (in her opinion), and she no longer wants to be protected.
It is later found out that So-Yoon is the reincarnation of Bub-Woon, and has Banya's mother's orb within her since she instinctively swallowed it as a baby, since she was dying from the cold tempertures of the moutain. Technically, So-Yoon is the orb itself. Until Bub-Woon awakens, she is currently a container for his soul.
- So-Yoon was born during winter.
- She does not like being compared to her Grandmother.
- Spirits like her scent and are attracted to her.
- She doesn't think it's fair to have Banya sacrifice his time for her if she became a Medium.