Tôkyô zankoku keisatsu

Ruka a police officer in a special squad formed to eradicate human mutations that have recently sprung into existence, the result of a virus created by a mad scientist simply known as Key Man. Killing these unwieldy mutants is no easy task, and Ruka, naturally enough, carries a samurai sword with her at all times. Despite being on opposite sides of the fence, Ruka and Key Man share a common bond: the murder of their fathers years earlier at the hands of the police, and both she and Key Man seek revenge for their dads' untimely demise.