Imagine, you are a girl student in high school. In Yandere Simulator you fell in love with a boy, who is some classes higher than you. Of course you can’t allow any other girl to approach him. So keep an eye and eliminate any lady who makes even a step towards your beloved boy. You can’t be honest enough and tell about your feelings. Perhaps, you are afraid to be ashamed. On the other side, the thoughts of that boy hanging out with another girl drives your character crazy.
Every week one of the school girls falls in love with that boy called Taro. She becomes a real rival for you. From that moment you are going to have 5 days to eliminate the girl away from Taro. Game finishes and you lose if the girl confesses her feelings to the guy. If your actions cause some problems and the main protagonist becomes expelled or ashamed the level finishes with the failure again. Methods can be different, some of them can be peaceful, some of them not. Only you can decide which way to keep.