A virtual world. Gunshots and bombs. A ruined city. Yet the only thing Kou remembers is the name of a case: "Gray Christmas". As the whole history about it comes back to him, his peaceful days come to an end.

Kawano Hatsuyuki is a third-year student, one of the rare delinquents at Shirosaki Gakuen. He reluctantly shows up in order to fulfill his graduation requirements. Hatsuyuki encounters a beautiful girl wearing a white dress. A few days later she transfers into his school.

After his mother passes away, Tomoya leads a life full of resentment. While on a walk to school, he meets a strange girl who questions if she likes school at all. He finds himself helping her, and as time goes by, Tomoya finds his life heading towards a new direction.

Night after night, the same dream of a guillotine. A headhunting serial killer. And the "knights" in black who follow soon after. Irrationality that defies the realm of common sense begins to assault and devour the city.

Mutsura Yuuto accompanies his friend on a holiday to Aqua Eden, an artificial island city where gambling is legal. His holiday plans are laid to waste after he gets involved in a kidnapping; to make matters worse, he ends up getting turned into a vampire.