Akatsuki is a powerful demon of illness that spreads into the victim, turns their eyes red, and slowly kills them. It usually takes the form of a strong monster connected to the victim's body. The only way to cure victims infected with Akatsuki is to slash their bodies with special anti-Akatsuki weapons known as "Crave". The group of people who possess and use these weapons are called "Kiri-Isha" (Slash Doctor). Hibiki, the protagonist of this story, is a Kiri-Isha. He partners with Kirisa, another Kiri-Isha. Their mission is to cure people infected with Akatsuki, but what could possibly lie ahead of them?