Premeditated Murder? Sister, She Is Not a Living Person

There is a monster inside me who calls me "sister". My name is Gu Shuyi, and I am the most transparent daughter in a wealthy family. And my sister, Gu Yingyi, although she has the same appearance as me, is strong and perfect, and is the proud daughter of heaven in the eyes of everyone. My parents gradually forgot my existence, and my classmates turned a blind eye to me. And she smiled and gave me "gifts" one after another: The blood-stained ribbon wrapped around the neck late at night, the strange dormitory where classmates sleep together... When the sister He Hua, who specializes in collecting weird things, appeared and told me that she was "contaminating" me into an ultimate resentment, I desperately discovered that if I killed her, I would also die. One of me and my shadow must die? Damn it, this is my "sister" Idiots, this time, it's my turn to control fate!