Seras Victoria was working for the police. However, in an unfortunate accident she was turned into a vampire. Now, as part of a special, secret organization in England that is in charge of destroying abnormal forces when they become dangerous to the country, she kills and cleans England from vampires. Grouping up with a totally crazy vampire and a few soldiers, she must now face a new type of vampires.
The two series are completely different featuring only loose connections when coming to conceptual levels. The two center around a servant and his master whom he must protect and obey. The comedy in kamen no meido gai makes you loosely think of hellsing, as both main characters tend to be very unaware of basic social norms.