High school girl Akane was leading a mundane and boring life. However, when she suddenly wakes up in what seems to be an unfamiliar school building, she finds herself with the beautiful transfer student, Ha. Their feet are chained together. A mysterious card states, "Only the last remaining pair will survive. If you remove the chains, it's game over. The time limit is one week." As a classmate tries to remove the chains and dies right in front of her, a panicked Akane hears Ha declare, "I will protect you!"...!? The death game exclusively for high school girls is finally starting!