Vampire Juuji Kai - Fallen Vampire

This is a spin off story that occurs about 3 years before Spiral. One of the main characters is Imari, who is in love with the kid who wants to be a detective, and which also quit school running after Kiyotaka, and it seems he's dating a murderer without

Plot: "I'm going to uncover the mystery of the Blade Children." World-class detective Kiyotaka Narumi's last words prior to his sudden disappearance continue to haunt his younger brother, Ayumu. The cheeky tenth-grader becomes further embroiled in the mystery when he is mistaken for the prime suspect in a murder at his school. Led by Ayumu's sister-in-law, Kiyotaka's wife and fellow detective, Madoka, the investigation into the murder gives Ayumu a chance to clear his name. But in doing so, he not only uncovers ties to the Blade Children but also more questions than answers about who and what they are.

Plot: Yoshino Takigawa is visiting his friend's family grave. After getting there, he encounters Evangeline Yamato, a woman in search for her friend Mahiro Fuwa, who left a month ago to find his family's killer without any clues to who it might be. Evangeline informs Yoshino that two places where Mahiro has been spotted have been quarantined, due to an epidemic. When Evangeline is questioning Yoshino at gun-point, Mahiro comes out of nowhere and swiftly saves him and can stop bullets in mid-air, claiming to have a deal with a sorceress; not just any, but the strongest sorceress, Hakaze Kusaribe, who promised to help find his family's killer with her magic so he can kill the killer himself. After saving Yoshino, Mahiro informs him about the epidemic, a curse that turns living things into metal, claiming the Kusaribe clan plans to revive the Tree of Zetsuen that could destroy the world.