With the sky turning red, the moon darkening, and monstrous creatures prowling the streets, Satsuki Kakeru and his best friend Yuka are left bewildered. They struggle to comprehend why they find themselves in this abandoned realm. However, their confusion dissipates when the "Red Night" repeats, endangering their lives once again. As they encounter four other individuals, they discover that Kusakabe Misuzu wields a sword with great proficiency, Tachibana Kukuri bears a striking resemblance to Kakeru's late sister and remains mute, Hirohara Yukiko possesses a vivacious personality, but turns into a ruthless killer when she removes her glasses, and Tajima Takahisa has the ability to control fire. The group bands together to survive and unearth the mysteries of this unfamiliar world, but when six ominous figures emerge, things take a turn for the worse.