"Never leave the apartment." That was the message from her mother. It seemed that this place had become a "quarantine zone" where no one could enter. High school girl Suzuka finds herself trapped in a locked-down apartment and must confront the mysterious unidentified lifeform "X" (Psi) in order to escape. Caught in a looping cycle of despair, she struggles to find a way out. Will Suzuka be able to return safely to her family?