Mochizuki General Hospital boasts some of the most well-trained (and well-endowed) nurses in town. But though these ladies spend much of their day battling sickness, their after-hours are spent fighting a very different sort of disease...Under the leadership of the hospital chairman, a handful of staff members and local teenagers form a group of mercenary assassins, targeting the "cancers" of society and excising those individuals before their wickedness spreads.

When two police detectives get involved in their operation, the nurses of Mochizuki Hospital must wield their instruments-katana, machine gun, and pistol-with even greater precision to excise the cancerous Masaki. As each nurse uses her particular specialty to dispatch Masaki's thugs, Arashi pursues the root himself. Arashi may struggle with his piecemeal identity, but treating this human virus is something both sides of him are sure of...

When a black-label target recognizes Mikoto on an extermination operation, Arashi is troubled by the realization that he knows little of his teammate's past. But as Arashi's unsympathetic attitude only widens the distance between them, Mikoto finds herself confiding in another-a new student, Chikage, whose burn scars are proof that her childhood holds painful tragedy as well...

Kaoru and Kaori are superpowered twins, the product of an unhinged, unethical maker. Their shadowy past merges with Hitsugi's own origins, a burden she carries as heavily as the coffin on her back. But Hitsugi is breaking free of her past and committing herself to doing Black Label's good work. The first order of business: wiping out a pair of red-haired blemishes on the face of the city