You live alone because your parents died in a fire and only know you have a friend named Shinyu since childhood, you call him sanyu,shinyu is an innocent and kind boy

One night you come home from work and wake up in a luxurious but dark house, you see Shinyu next door so you work together to get out but it's not easy because there is a masked man who wants to hurt you so Shinyu pushes him into the warehouse, You go back to looking for the key in a hurry and panic until he finds the key, a voice calls from a man in the warehouse calling him, not Shinyu but Junghwan and at that moment you know that the writing on the blackboard is a plan to kill your parents, a plan to kidnap you, it's not shinyu but Junghwan, shin junghwan. your neighbor and shinyu used to be, the memory comes back to your head, junghwan who started the fire in your house and tied shinyu up in your house until he died with your parents, all this time he pretended to be shinyu and will continue like that when you faint when you see him and wake up in a state of not remembering anything, Junghwan always pretending became shinyu for you