Ary, the baby daughter of a noble woman in the demon kingdom, is ugly because her mother refused the blessings from her uncle. So Ary was swapped with baby Alex, a human beauty. However, Alex was also cursed by the same guy; the curse is… the 3 princes of the demon world will all be in love with her, but she can only love the "shadow."
Some years later, the noble woman, wanting her own daughter to become wife of the crown-prince, plotted to kill Alex and brought back the ugly daughter from the human world. But the crown-prince only cares about his childhood friend, Alex.
Alex, saved by the "shadow," went to the human world to find the "stick" of prince Ji Woo, who she loves the most but, instead, Alex got her memories erased and a new identity, the adopted granddaughter (niece?) of the chairman of a big corporation. (The chairman has the stick.)
There, she lived like normal human, until prince Ji Woo appears...