The main character reincarnates into Amy, a side character of a novel that she had once read.
In the original novel, Amy’s sister was the first love of the male lead, but then got brutally killed by that guy.
Due to growing up in a demolished family, the male protagonist becomes cruel and forms a shape of an assisinate. He has also been suffered a curse that driving he appears as an adolescent during the day. Can he release from the curse? What will happen next?