Lee Rowoon is a college student cursed to transform into a doll every night at midnight. Her dream is to break the curse, live a normal life, and grow closer to Ha Hyun, the upperclassman who happens to be her ideal type. One day, Rowoon unexpectedly runs into Dae Gilseong, an older acquaintance she once trusted and admired more than anyone else. But Gilseong is none other than the person who stole the “Key of Blessing” ten years ago, a magical object that protected her from the curse and held the only means of breaking it. Furious, Rowoon chases after him, but just as she is about to tumble down the stairs, Gilseong tries to save her, and the two accidentally share a kiss. Unfortunately, the unexpected side effect leaves Rowoon permanently trapped in her doll form, unable to return to normal. Soon afterward, Rowoon’s uncle, a wizard, arrives to take care of her and demands that Gilseong return the key. Gilseong reveals a gemstone embedded in his chest and explains that the key was mysteriously absorbed into his body one day. He has spent the past ten years searching for Rowoon, hoping to reverse what happened. With the key now fused to Gilseong, the only way Rowoon can temporarily maintain her human form is by kissing him. Left with no other choice, she begins secretly living with him. Eventually, the condition for completely breaking the curse is revealed. Gilseong, who has become the key itself, and Rowoon, the girl under the curse, must share a kiss while their feelings are perfectly aligned. Whether those feelings are born of hatred… or love.