After losing his sister seven years ago, Satsuki Kakeru led a vacant life, only able to return to his normal days with help from his childhood friend Minase Yuka and other friends at school.
Suddenly one day the sky turns red and the moon turns black. Everyone around Kakeru and Yuka disappear and monsters start roaming the streets. They are only able to run away and hide and after a while, the world returns to normal. But just when they thought this world was a dream, the Red Night occurs again.
Kakeru and Yuka manage to find four other humans involved in this mysterious phenomenon: Kusakabe Misuzu, a red-haired onmyouji swordswoman, Tachibana Kukuri, a strange mute girl who looks like Kakeru's deceased sister, Hirohara Yukiko, a lively young girl who reverts to the personality of a cold killer when her glasses are removed, and Tajima Takahisa, a young pyrokineticist with a heated attitude to boot.