Vampires—supernatural beings that feed on the life essence of the unsuspecting at night—have been around for centuries. However, high schooler Karin Maaka is unusual, even among her own kind. Unlike her vampire family, ever since she was a child, Karin has suffered from polycythemia: a rare disorder which causes her to periodically produce excessive amounts of blood. And the more blood she produces, the more anemic and lightheaded she gets, ultimately leading to frequent nosebleeds. Her only solution? Force her excess blood onto random strangers, which surprisingly causes these "victims" to become livelier and happier than before. With her siblings—Anju, her reserved yet affectionate younger sister, and Ren, her womanizing elder brother—helping her abilities remain a secret by altering the affected humans' memories, no one is the wiser. That is, until Karin's newly transferred classmate, Kenta Usui, finds her behavior suspicious. And to make matters even more complicated, Karin feels her blood reacting unusually to Kenta's presence.

Lily Bridge, a young journalist, arrives at Arkham City, hoping to find a big scoop. However, with all the strange things occuring around the city, only the exceptional findings are news-worthy, such as the mysterious mecha known as Demonbane. However, upon finding a small piece of machinery that seemed to be connected with the Hadou Combine, Lily is determined to find the truth. Little does she know, she enters into a dark world, involving herself with Demonbane and the powerful forces that control the city.

In this prequel to the "X" TV series, a beautiful, young, bedridden dreamgazer named Kakyou remembers the life and death of a remarkable young woman whom he met in dreams. He also recounts his dreams of a tragic future in which the fate of the Earth will be decided.

His destiny has finally arrived as the young Shirou Kamui returns to Tokyo after 6 years. A powerful psychic, Kamui vows to protect the happiness of his childhood friends Fuuma and Kotori, even if it means avoiding them. But fate is cruel, whether or not Kamui wants to be involved; he holds the future of the world in his hands, given the choice of becoming a Dragon of Heaven or a Dragon of Earth. The Seven Seals gather, and so do the Seven Angels; all individuals who have their destiny carved out as one who would battle for the fate of the world. What future will Kamui choose to become reality?