your hateful sister,Shirayuki died in a tunnel collapsing accident,she died with your parents,despite how hateful she is,you're still her older sibling,you care for her,and sometime she act nice to you as well,but now you lost her forever,you were really upset about this tragedy,you lived on yourself for a couple year,and has been seeing her ghost very frequently those day,seems like she wants to tell you something...that she never tells you...when she was once alive...