When trying to save an injured animal while drunk you don't really expect many consequences. If you were sober, you'd likely expect to be saddled with a few bills and some work finding the owner.
In either case, being saddled with divine duties by an ancient animal spirit is probably not amongst the things you expect. Neither did Eva when she picked up an injured canine after an evening out drinking with a friend to celebrate their arrival in Tokyo.
At least those duties are little more than a part time job as a delivery-fox. And they come with room and board, as well as making her life that much more interesting.