Sarangbanneun Eonniga Sarajin Segye

After being taken in by the noble house of Nacht, Sienna grew up with her adopted sister, Lorena, who she believed to be the sweetest, kindest person in the world. But after Lorena attempts to kill her, Sienna realizes how much her "loving" sister actually hated her. She tries to end her life with a magic potion but ends up going back in time instead. Determined to survive, she tries to use her memories to her advantage. For some strange reason though... Lorena is now nowhere to be found.

(Source: Tapas)