You are playing as one of the many students at Kodokuna Ki Kōkō (Lone Tree High School), it has always been foretold that this particular school is cursed and over the years many parents have even pulled their children from the building in a panic. The legend arose from an unexpected death twenty years ago of a student called Nahi Nakamura who died from a collapse in the main hall from a broken board on the stage, during a performance. She fell into the basement and was suspected to have died upon impact, however, when the police found her, she wasn't whole. The only suspect of the event to find was Hideaki Asanuma - her supposed best friend. He was discovered beside her mangled body, crying and covered in her blood but was never seen at the performance in the first place - it's said that he has never spoken a word since the event and lives inside a mental asylum, driven crazy from the event. It is now rumoured that the girl's spirit wanders the halls and waits for the right body to possess and control as her own body parts were never re-attatched.
Note: The game-play will consist of different chapters and characters to control with different endings. The way you play will determine if you can continue to the next chapter, if not, you'll have to go back and figure out another way to progress.
Suggestions: I also recommend reading this without any other light than your screen, playing some creepy music/soundtrack/instrumental to peak some reactions and playing it late and/or on your own.