Dan O is the beautiful and only daughter of a wealthy family who still has a heart disease despite having been operated on multiple times. After sensing weird things happening to her, Dan O finds out that she and everyone else around her live in a fantasy world inside a teen fiction comic book entitled Secret, of which she is only an extra character. As a character in Secret, she has been engaged to Gyeong, her crush, for almost a decade and could possibly die soon due to her health condition.
(Source: Wikipedia)
