What is black cat the anime about?

There are several anime series and movies that feature "Black Cat" in their titles, but they are all different. To help you, please specify which "Black Cat" anime you're referring to. For example, are you asking about:

* Black Cat (2005 anime series): This is a popular action-adventure series about a former assassin who is trying to make amends for his past.

* The Black Cat (1966 anime film): This is a classic anime film with a mysterious plot about a thief and a cat.

* Black Cat (2006 OVA): This is a short anime film related to the main "Black Cat" series.

Once you tell me which "Black Cat" you're interested in, I can provide more information about the plot and characters.