Kitsune- a powerfull soul

How do you become a Demon fox?

The first way is that you are born with it.
It's comes from you're parents or just one of them.

The second alternative is a way more horrifying then that. A Kitsunes soul can take possession of a innocent unborn baby.

The third alternative which is LOOT nicer then the second one. If you want you can share a Kitsunes soul with a other Kitsune. Which I would personally prefer...