The family of Ravenwind is set on a planet that is commonly refered to as "Earth". However, this Earth is different from the one you know (obviously), in this world, there are people who have super-natural powers, they vary from ability to heal fast to something as big as to turn into a monster. It is estimated that about half of the Earth's population posseses some kind of
super-natural power.
There is a large group of people with super-natural powers called "Justice force" but some call it the
"Hero Force". I think it is easy to imagine what they do, bring justice and destroy evil, the casual. There are some "evil" groups
with super-natural people but none of them are major. The Ravenwind's mansion is located somewhere in the Japan, Chiba. Each
Ravenwind family member is blessed with a power that keeps them young for almost 500 years, similar to vampires but they're not actually vampires.

Ps : here's the family tree

A poorly made family tree :D