The private school, Seigakuen, which is proud of its 60-year tradition, is built on a hill overlooking the entire city. However, since the school was founded, various ghost stories and urban legends, including the "ghost of the old school building", have been circulated among students. One day, a student named Shintani Sadaichi met a mysterious female student wearing a black sailor suit that is now discontinued. The female student claimed that she was Yuko, the "ghost of the old school building", and hoped that Sadaichi would help her find out the cause and truth of her death.