I love the premise behind this series just sort of appeals to my sick sense of humour. Take terminally ill girls with no real families cure them turn them into cyborgs, condition them with a dependency to and willingness to anything for their handler (older brother figure). Then train them as assassins and use them to hunt down mafia types.
This is a simple run down of seeds of the story, however the the anime is so much more the girls all have their own personalities and each treat and are treated by their handlers differently. Some of the most touching bits are just the girls together in one of their rooms having tea and talking behaving like normal girls or not.