This is an abandoned school. After several cases of students dying due to bullying and suicide, the students are terrorized by angry ghosts. Some got a trauma, and some student go missing. In the end, this school was closed for safety reasons.

You are a former student here. You set foot in this school again to find clues about your missing sister in this school. When entering the classroom, you see a beautiful, pale-faced girl looking at you with vacant eyes

...who are you?