Akatsuki

Akatsuki: a powerful demon of illness which spread into victims, turning their eyes red, and slowly killing them. Usually, they take form of a strong monster connected to the victim's body. The only way to cure the victims infected with Akatsuki is to slash the victim's body with special anti-Akatsuki weapons, known as "Crave." The people who possess and use these weapons are called "Kiri-Isha" (Slash Doctors). Hibiki, the protagonist of this story, is a Kiri-isha. He is partnered with Kirisa, another Kiri-Isha. Their mission is to cure people infected with Akatsuki.(Source: Ju-da-su)