Set in a future-world vision of Tokyo where the police have been privatized and sour self mutilation is so casual that advertising is often specially targeted to the"cutter" market, and this really may be the story of samurai-sword-wielding Ruka and her mission to avenge her father's assassination. Ruka is a cop out of a squad whose mission will be to destroy homicidal mutants referred to as"engineers" owning the capacity to transform virtually almost any injury to some weapon.