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 grapples with Lee's bombshell that drinking human blood can have regenerative, strengthening powers on devil bodies and Lee offers to share what he knows if Anzai's comrades hide him away. Meanwhile, Zero Seven, the sniper, faces the consequences of her rebellion as Zero Two works to tie up loose ends from the Ikebukuro incident, and reveals that he has an old connection to Anzai..."

Tsukasa insists on seeing that Oryo is cared for at a hospital, defyingAnzai's wish that she stay hidden at their safe house. Before she can even make it inside the hospital, Tsukasa is taken hostage by a desperate Zero Seven, who eventually makes a surprisingly humane choice when facing off with her old comrades. Tsukasa and Anzai decide to take the next step in their relationship, and the old doctor from ONLO reveals why he's in town..."