After school, Sena Kadowaki (Miori Ichikawa) goes up to the school rooftop to return a handkerchief to Yudachi Tsutsui (Ririka). While waiting for Yudachi , Sena falls asleep.
When Sena wakes up, she finds that it is now dark and she is locked up at her school. Her cellphone is not working. A light turns on and the world is dyed red. Girls begins to fight with each other and even kill each other. Can Sena survive?
