Tsukasa, a college student, is rescued from an attack by a devil, one of many vampires that can blend in among the human population. Anzai, her savior, is a half-devil who exploits his supernatural gifts as a member of a shadowy police task force that specializes in devil-related crime in Tokyo. As Anzai continues to keep guard over Tsukasa, the two quickly forge a tentative bond—one that Anzai fears will test his iron-clad rule of never drinking human blood…
Anzai travels to Obihiro to learn the circumstances surrounding his birth as part of the Hybrid Plan, and the reason why Midori chose Tamaki for a partner. Tsukasa is also at ONL to read academic journals on devils, and both she and Anzai are notified that the “no contact” order is rescinded. As the two decide to take the next step within the clinical confines of the laboratory, Anzai begins to understand what drives him to chase after devils…