The Inugami is a familiar of western Japan, said to be an artificially created dog spirit. A family that commands an Inugami gains wealth through its power, but the possessing spirit is believed to cling to that family for generations.
The core is that benefit and curse never separate. The "Inugami-mochi" families that keep one became objects of fear and avoidance in their villages, bound to an inherited yoke from a power that, once taken in, cannot be cut loose.