Satsuki Kakeru is at a loss for what to do as the sky turns red, the moon becomes black, and monsters start wandering the streets. They strive to figure out why they've been sent to this weird world, which appears to be empty save for them, with the help of his best friend Yuka. When the "Red Night" comes to a close, Kakeru and Yuka believe it was all a dream, until it happens again, leaving them in a hazardous scenario. They meet four other people in a similar situation: Kusakabe Misuzu, an expert swordswoman, Tachibana Kukuri, a strange mute girl who looks uncannily like Kakeru's deceased sister, Hirohara Yukiko, a lively young girl whose personality reverts to that of a cold killer when her glasses are removed, and Hirohara Yukiko, a lively young girl whose personality reverts to that of